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296 Cards in this Set

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1: What does MRS GREN stand for?

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition

How does the binomial name system work?

Each animal gets two names: the genus name (the animal's group of species) and the trivial name (just a name for it)

What is a species?

A group of individuals that live together and breed together to produce fertile offspring

What are invertebrates?

Animals without a vertebral column (backbone)

What are three phyla (subdivisions) of invertebrates?

Nematodes aka roundworms (worms with thread-like bodies, not made up of segments, often parasites), e.g. whipworms

Annelids (worms made up of segments, may have paddle-like extensions), e.g. earthworms

Molluscs (soft unsegmented bodies, muscular 'foot' used for burrowing or movement, may have shells), e.g. snails and slugs

Anthropods are...

segmented animals with jointed legs and an exoskeleton

What are the four classes that anthropods are classed in?

crustaceans (head-thorax, abdomen, gills), myriapods (centipedes/millipedes), insects (head, thorax, abdomen, six legs, wings), arachnids (two parts, eight legs)

Vertebrates are...

animals that have a vertebral column aka a backbone

What are the five classes that vertebrates are classed in?

Fish: water, streamlined, fins, scales

Amphibians: live on land & breed in water, external fertilisation, smooth & moist skin, breathe underwater through skin, breathe on ground with lungs

Reptiles: dry scaly skin, internal fertilisation but external development (eggs), dry habitats

Birds: feathers, wings, no teeth (beaks), warm-blooded, internal fertilisation but external development (eggs)

Mammals: hair/fur, internal fertilisation and development, mammary glands, lungs, warm-blooded

Bacteria are...

cells with no nucleus, just a loop of DNA within the cytoplasm. May have flagella (singular flagellum) for movement. Feed using enzymes that digest surroundings into simple molecules, which are absorbed. Can divide once every 20 mins under good conditions, can quickly form a colony.

Virus are...

not cells but a few genes inside a protein coat. Can only be seen under an electron microscope. They are parasites that enter cells (hosts) and force them to make new viruses. Do not respond to antibiotics.

Fungi are...

made up of threads called hyphae, this makes up the mycelium. The hyphae grow over the food source, releasing enzymes. These enzymes digest the food outside the fungus, the digested food is the absorbed by the hyphae.

Reproduce by making spores that can be carried by wind. Most fungi feed on decaying/dead matter but some are parasites.

Flowering plants are...

multicellular (like all plants). Each cell has a cell wall made of cellulose.

Dicotyledons are...

'normal' flowering plants: roses, sunflowers etc. Leaves are often broad with branching veins. Have two cotyledons (seed leaves) in each seed.

'normal' flowering plants: roses, sunflowers etc. Leaves are often broad with branching veins. Have two cotyledons (seed leaves) in each seed.

Monocotyledons are...

usually grasses or cereals like maize. Another example is palm trees. Leaves have parallel veins. Grasses and cereals have long, narrow leaves. Have one cotyledon (seed leaves) in each seed.

usually grasses or cereals like maize. Another example is palm trees. Leaves have parallel veins. Grasses and cereals have long, narrow leaves. Have one cotyledon (seed leaves) in each seed.

What does dichotomous mean?

dividing into two

What's a dichotomous key used for?

identifying organisms

What's a dichotomous key?

something like this

something like this

14: What is asexual reproduction (plants)?

It results in the production of genetically identical offspring from one parent.

What is sexual reproduction (plants)?

It involves the fusion of male and female nuclei to form a zygote, producing offspring that are genetically different to the parents.

What is binary fission?

It is a form of asexual reproduction. It is the way that bacteria reproduce. One cell -> DNA splits -> cell starts to split -> two cells

How do potatoes reproduce?

who cares


What is spore production in fungi?

It is a form of asexual reproduction. It is the way that fungi reproduce. The fungi makes spores, when a spore lands on a damp surface it splits open and a hypha (a thread) grows out. Hypha grows over the surface of bread to form a dense network called a mycelium. Eventually, short hyphae grow upwards and produce sporangia (spore cases) at their tips. In the sporangia, hundreds of spores are formed asexually by the division of nuclei. When ready, the sporangia break open and spores fly free.

What are stem tubers?

They are how potatoes reproduce. Stem tubers are swollen underground stems that grow from the parent plant, they are filled with starch. The potatoes die at the end of the growing season, leaving the tubers to survive over winter - however, farmers usually pick them out and sell them. Some are kept as 'seed' potatoes to plant the next year. When they start growing, shoots and roots emerge from the potato's growing points, known as 'eyes'

What are the advantages and disadvantages of asexual reproduction in plants?

Asexual reproduction may produce several plants very rapidly, but there is no variation in offspring like in sexual reproduction. This means that if a disease affects one of them, it affects them all. Asexual reproduction usually means that the plants all grow around the same space, meaning there is competition for resources.

stamens are...

the male sex organs

carpels are...

the female sex organs

Describe insect-pollinated plants.

- Flowers have sepals to protect the flower in the bud when it's developing.

- Bright scented petals to attract insects

- Stamen consists of anthers (where the pollen is made) and filaments (stalks to hold the anthers).

- Each carpel is made up of a stigma (pollen grains land on this during pollination), style and ovary

- Many have a nectary at the base

Describe wind-pollinated plants.

- Inconspicuous (no bright petals)

- Feathery stigmas that hang outside the flower (so they can catch pollen from the wind, like a net)

- Anthers that hang outside the flower (so the wind can blow the pollen away)

What kind of pollen do insect-pollinated flowers make?

smaller quantities of sticky and spiky pollen that attach to insects

What kind of pollen do wind-pollinated flowers make?

large quantities of light, smooth pollen that the wind can carry easily.

What is pollination?

The transfer of pollen from the anther of a plant to the stigma of another plant of the same species. May be carried out by insects or wind. When an anther is ripe, it splits open and release pollen for this to occur.

Pollination is needed in order to bring the male gamete (inside a pollen grain) near to the female gamete so that fertilisation can occur.

What happens in insect pollination?

Bees land on the petals, they have long tongues that let them reach the nectaries at the base of the petals - they feed on this. The anthers are positioned so that sticky pollen will stick to the bees when they push their heads down to the base of the petals.

When the bee enters another flower, pretty much the same thing happens again but instead of brushing against anthers they brush against ripe stigmas and deposit their pollen - pollination is achieved

What happens in wind pollination?

The anthers hang outside the flower so that pollen will be released when the wind blows them. The stigmas are feathery and also found outside the flower so that they can act as a net to catch pollen grains in the air. These flowers have smooth, light pollen grains that are carried by wind easily. The anthers produce many many pollen grains so that some will, by chance, find their way to another plant of the same species - most of the pollen will be lost.

What is self-pollination?

What are its (dis)advantages?

It involves the transfer of pollen from the anthers to the stigma of the same flower.

Much less variation since genetic material is not exchanged. However, it is good for if there are no pollinating insects, and for plants growing in isolation from plants of the same species.

What is cross-pollination?

What are its (dis)advantages?

The normal way of plants getting pollinated. Pollen from the anthers of a plant to the stigma of another plant of the same species.

It ensures genetic exchange between plants, thereby resulting in greater genetic variation upon which natural selection can take place.

What happens when a pollen grain lands on a stigma?

It produces a pollen tube that grows down the style to an ovule in the ovary. As it grows, it carries the male gamete nucleus with it. When the first pollen tube reaches the ovary, it enters the ovule through a small whole called the micropyle. Then the male gamete nucleus fuses with the female egg cell nucleus, forming a zygote.

What is fertilisation in plants?

when the male gamete nucleus from the pollen tube fuses with the egg cell nucleus inside an ovule

What happens to the zygote after fertilisation?

It divides and grows into an embryo inside an ovule which now forms the seed, the ovary forms the fruit containing the many seeds

Each seed is made up of...

outer testa: seed coat - tough protective layer

embryo: radicle (becomes the root) and plumule (becomes the shoot)

cotyledons: starch and proteins for energy to grow

Fruits and seeds are dispersed by...

wind or animals

Why do fruits/seeds have to be dispersed?

Without dispersal, new plants would be too crowded. They compete for light, water, nutrients etc.

What do germinating seeds require?

Water, oxygen and warmth

What is growth?

A permanent increase in size and dry mass by an increase of cell number/size.

What is development?

As a plant grows, its cells become more specialised and the organism becomes more complex - this is development. In plants, cells from cell division can become mesophyll, xylem, phloem etc.

How can you measure growth?

One way is to find the wet mass of a plant each day, but this is not a fair test because much of the mass is water.

A better way is to remove the water by heating the plant material and then weighing it (repeat until the weight doesn't change anymore) - the dry mass. But this kills the plant.

What are the organs in the human male reproductive system?

Testes, scrotum, sperm ducts, prostate gland, urethra and penis

How do sperm cells compare to egg cells?

Sperm cells are much smaller, are much more numerous, have barely any food stored and move on their own using tails. Egg cells move by being wafted along by cilia and peristalsis, they have lots of protein and fat as a foodstore. They both have 23 chromosomes (haploid)

What are the organs in the human female reproductive system?

ovaries, oviducts (fallopian tubes), uterus, cervix and vagina.

What happens during sexual intercourse?

The male's semen is transferred into the vagina of the female.

What is fertilisation in humans?

When the sperm cell fuses with the egg cell in the oviduct of the female.

How does a sperm fertilise an egg?

The sperm's head digests its way into the egg using enzymes, the tail is left outside. The sperm nucleus fuses with the egg's to become diploid (46 chromosomes). A membrane immediately forms around the zygote to stop other sperm hitting it.

What does the zygote start to do immediately after fertilisation?

It divides to form a group of cells called the embryo, which passes down the oviduct (peristalsis and wafting cilia) and implants itself into the lining of the uterus (which has thickened in preparation for this).

How is the placenta formed and what does it do?

After implantation, part of the embryo grow into finger-like villi that penetrate the lining of the uterus. They are surrounded by blood vessels that carry nutrients and oxygen.

The placenta has a large surface area for gas exchange and diffusion of food and waste between fetal blood and mother's blood.

What is the amniotic sac/amnion

Contains amniotic fluid. A sac that protects the baby from mechanical damage and keeps its environment sterile. Because his body parts are growing so fast, the fluid provides lubrication that keeps them from growing together.

How is the baby pushed out during labour?

Muscles in the uterus wall contract.

What is done to the baby once it's out?

The umbilical cord is cut and tied. The placenta passes out of the uterus as the afterbirth.

What is ante-natal care (during pregnancy)?

It involves the mother having enough calcium (baby's bones), iron (extra red blood cells), carbohydrates (energy to move a larger body mass) and protein (to make new tissues). Also, the mother should avoid drugs and smoking because the ill effects from these can pass on to the baby.

What are breast milk's advantages over formula milk?

Contains antibodies that give the baby passive immunity (it cannot create the antibodies itself, it just has them) to diseases. It is also free.

What is menstruation?

During the menstrual cycle a follicle develops inside the ovary and the lining of the uterus thickens. If implantation does not occur, the lining of the uterus and vagina break down (and pass out as a period).

How is the menstrual cycle controlled with hormones?

The pituitary gland (in the brain) releases FSH (follicle stimulating hormone), which stimulates the development of a follicle inside the ovary and the secretion of oestrogen.

This oestrogen then stimulates the thickening of the uterus lining, inhibits FSH production (so there are no more eggs/follicles) and causes the pituitary to release LH (luteinising hormone).

LH then stimulates the follicle to release its egg (ovulation), leaving behind a yellow body.

The yellow body starts making progesterone, which maintains the lining of the uterus.

If pregnancy occurs, progesterone and oestrogen continue being produced.

What is testosterone?

The male sex hormone, stimulates puberty

What is oestrogen?

The female sex hormone, stimulates puberty

What happens in puberty in boys?

growth of the male sex organs

testes start to make sperm cells

growth of hair on the face

voice breaks

development of muscles in the body

What happens in puberty in girls?

growth of the female sex organs

start of the first menstrual cycle and the first period

growth of hair on parts of the body

growth and development of breasts

widening of the hips

What can infertile females do to have children?

They can take fertility drugs containing FSH to stimulate the release of eggs thereby increasing chances of pregnancy.

What can infertile males do to have children?

Couples may opt for artificial insemination where a sperm donor is used to fertilise the woman's fertile eggs.

What are some chemical methods of contraception?

the pill and spermicides

What are some mechanical methods of contraception?

condoms, femidoms or a cap/diaphragm (placed over cervix)

What is a natural method of birth control?

the rhythm method, which relies on calculating when ovulation is most likely and abstaining from sex during that time.

What are the surgical methods of birth control?

For a man: vasectomy (tubes cut and tied)

For a woman: sterilisation (oviducts cut and blocked)

What is HIV?

Human Immunodeficiency Virus. Transmitted in semen or in blood. Develops into AIDS.

How can the spread of HIV be reduced?

condoms during sex

not sharing needles between druggies

careful screening of donated blood for transfusions

How does HIV weaken the immune system?

It destroys T lymphocytes (which are supposed to stimulate other lymphocytes to create antibodies), meaning that fewer antibodies are released to fight infections. This makes people susceptible to other diseases, such as TB

What is gonorrhoea?

Bacterial disease spread through intercourse. Cannot survive outside the body. Causes 'unpleasant' discharge from sex organs. Can cause sterility if left untreated, there is effective treatment through antibiotics. Its spread can be controlled by tracing and treating sexual contacts of an infected person. Its spread can be prevented by the use of condoms or just having one uninfected partner.

2: What organelles are found in both animal and plant cells? What do they do?

Cell membrane: barrier, allows simple substances to leave and enter (e.g. oxygen, water, CO2), controls movement of other substances (e.g. glucose), semi-permeable

Cytoplasm: where many chemical reactions take place

Nucleus: controls cell's activities, controls how cells develop

What organelles do only plant cells have? What do they do?

Cellulose cell wall: stops cells from bursting when they fill with water, maintains structure/shape, allows water and other substances to pass through freely (fully permeable)

Chloroplasts: photosynthesis, starch storage

Vacuole: contains cell sap, maintains shape/firmness, holds salts and sugars

What do cells do during their early development?

Changes structure and/or shape, in order to become more specialised for specific purposes.

Ciliated cells are...

found in the air passages of the lungs and in the oviducts of the female reproductive system. Have cilia (similar to hair) on their surface. They beat back and forth to move things along their surface like a conveyor belt: e.g. mucus up to the nose/throat and eggs from the ovary down to the uterus

Xylem vessels are...

Cylindrical and empty, arranged in columns like pipes. Walls are thickened with lignin (waterproof material). Allow water and ions to move up from the roots to the rest of the plants.

Root hair cells have...

long extensions to increase their surface area, thereby making them more efficient at absorbing water/ions for the plant.

Muscle cells...

make up fibres that can shorten or contract, thereby moving whatever they're attached to (usually a bone, but they are also in the gut and the heart)

Red blood cells...

contain the protein haemoglobin to transport oxygen. Shaped like flattened concave discs to provide a large surface area to carry oxygen on. Have no nucleus for some reason lolidk

What is the equation for magnification?

A group of cells with the same function grouped together is a...

tissue. E.g. cardiac muscle tissue (for the heart)

A group of tissues working together to perform specifics functions is a...

organ. E.g. the heart

A group of organs with related functions are an...

organ system. E.g. the circulatory system of the heart + blood vessels

A group of organ systems make a...

organism. E.g. your mum

3: Diffusion is...

the net movement of molecules from a region of high concentration to a region of low concentration down a concentration gradient.

Factors that affect diffusion are...

size of molecule, distance, surface area, temperature and the steepness of the concentration gradient.

Osmosis is...

diffusion of water molecules from an area of high water potential (dilute) to an area of low water potential (concentrated) through a semi-permeable membrane.

What is a partially permeable membrane?

A membrane that allows small molecules through but not larger ones.

How does water pass into plant cells?


What do you call a plant cell that is full of water?

What is their purpose?

They are turgid. Turgid cells provide support for leaves and young stems. Plant stems and leaves that have lost water wilt.

What happens when plant cells with water in them are put into a liquid of high salt/sugar conc?

Water passes out through osmosis, they are no longer firm - they are flaccid. As more water leaves, the cytoplasm moves away from the cell wall and the vacuole shrinks - the cell is plasmolysed now.

What happens to animal cells when they lose or gain water through osmosis?

They have no cell wall to resist water gain, therefore they burst when in water. They shrink when in high concentrations of salt/sugar.

What is active transport?

the movement of ions or molecules across the cell membrane, against a concentration gradient, using energy from respiration.

How is this possible?

There are carrier proteins that take in the molecules. They use energy from respiration to change shape and bring them into the membrane.

There are carrier proteins that take in the molecules. They use energy from respiration to change shape and bring them into the membrane.

Name two process active transport assists in.

It enables root hair cells to take in ions.

It enables the epithelial cells of the villi to take up glucose.

4: What is an enzyme?

They are biological catalysts that increase the rate of chemical reactions. Their main purposes are: building large molecules from small ones, breaking large molecules into small ones and converting one molecule into another.

List some general properties of enzymes.

They are all proteins.

Each enzyme catalyses one reaction.

They can be used over and over.

They are influenced by temperature (can be denatured).

They are influenced by pH (have optimal pHs)

Explain the 'Lock and Key' model for enzymes.

Enzymes affect substances called substrates. The substrates are affected on the active site of the enzyme. Only certain substrates' shapes (the 'keys') can fit certain enzymes' active sites (the 'locks').

How does increasing the temperature affect enzyme efficiency?

It increases it, until the enzyme reaches its optimum temperature. After this, the enzyme denatures and efficiency decreases.

This is because temperature leads to more kinetic energy, which leads to more successful collisions being able to take place.

If the temperature is too high, the bonds in the enzyme break down and its active site shape changes, meaning it cannot react with the right substrates - it is denatured.

How does changing the pH effect enzyme efficiency?

Most enzymes work best at a specific pH (optimum pH), so the efficiency increases as it heads towards that and vice versa.

When the pH is too far from the enzyme's optimum pH, the bonds in the enzyme break down and its active site shape changes, meaning it cannot react with the right substrates - it is denatured.

How is beer made using enzymes?

Stored starch in seeds is broken down by amylase into maltose during germination (the seeds are put into the optimal conditions for this). This is the sugar used by yeast in the fermentation process to make alcohol.

Stored fat in seeds like sunflower ones is broken down by lipase.

Describe a fermentation vessel.

Big tank made of stainless steel. Filled with a medium containing the right nutrients. Microorganisms (e.g. bacteria, or a fungus like pennicillium) is added. The fungus grows well in this. Scientists can identify the genes required for certain enzymes and inject them into bacteria.

A stirrer keeps the microorganisms suspended so they can always access nutrients and oxygen.

An air supply is added for their aerobic respiration.

A water-cooled jacket keeps the temp constant.

Probes monitor the temperature and pH.

How is fruit juice extracted?

Pectinase is an enzyme used to break down pectins, which are molecules that act like 'glue' in plant cell walls. This means the fruit is easier to crush for its juice. It can also be used for softening vegetables.

How do biological washing powders work?

They include one or more of the following enzymes.

- protease for protein stains such as blood or grass.

- lipase for fat in grease stains from butter or mayo.

- amylase for starch in food stains

- cellulase to break down cellulose fibres on the outside of cotton fabrics to remove the dirt from them.

They have been modified to endure the high temps and alkalinity of washing cycles. Though some newer ones work at temps as low as 15 degrees Celsius. These enzymes degrade into harmless substances afterwards, unlike some chemicals used non-biological washing powders.

5: What elements are carbohydrates, proteins and fats made from?

Carbohydrates: C, H, O

Fats: C, H, O

Proteins: C, H, O, N, S

What is nutrition?

Nutrition is the intake of raw materials to provide the substances necessary for growth and repair.

The nutrients seven are: carbohydrates, proteins, fats vitamins, minerals, water, fibre

Explain the different types of carbohydrates.

Carbohydrates contain sugars and starches.

There are simple sugars (e.g. glucose from photosynthesis). Two molecules of simple sugars can join to form a complex sugar such as sucrose (normal sugar, used in tea/coffee), maltose (malt sugar) and lactose. Many simple sugar molecules can join to form a complex carbohydrate such as starch (made of glucose, functions as a store of glucose in plants) or glycogen (similar to starch but in animals).

How are proteins made up?

They are strings of amino acids. There are about 20 amino acids. Enzymes, haemoglobin, antibodies and some hormones are all examples of proteins. The amino acids connect to each other with peptide bonds.

How are fats made up?

Each fat molecule is a glycerol molecule + three strands of fatty acids. Like




ascii drawing is hard

What is the test for starch?

Iodine solution goes blue-black when it touches starch.

What is the test for simple sugars?

Add Benedict's Solution to a test tube of the solution you want to test, put the test tube into hot water. Benedict's Solution starts out as bright blue, you can tell how much sugar is present by the colour it turns: from green (meaning little sugar) to brick red (meaning lots of sugar)

What is the test for proteins?

Biuret's solution turns lilac in their presence.

What is the test for fats?

Submerge the subject with ethanol in a test tube. Put a stopper on the test tube and shake it. Add some distilled water to make it half-full. Shake again. If there is a cloudy white emulsion, then fat is present.

What is the general use of carbohydrates from our diet?

A ready supply of energy. Simple sugars are absorbed almost instantly for a quick burst of energy (sweets etc.). Sources are: rice, bread, cereal, yams, sugar and honey.

What is the general use of proteins from our diet?

To grow and develop, you need it to make more cells. The body digests proteins into amino acids, and uses these to make its own proteins. Sources: fish, meat, milk, nuts

What is the general use of fats from our diet?

A long term energy store. Also as thermal insulation. Sources: butter, cheese, fat in meat/fish, nuts

What is the general use of water from our diet?

For chemical reactions to take place in solution, sweat, transporting substances in the blood, urine.

What are the sources, uses and deficiency syndromes of vitamin C, vitamin D, iron and calcium?

C: Citrus fruit. Tissue repair, disease resistance. Bleeding gums (scurvy)

D: Fish oil, milk, butter, made under the skin in sunlight. Strengthens bones and teeth. Soft/bendy legs (rickets)

Iron: Liver, meat, cocoa, eggs. Formation of haemoglobin. Tiredness, lack of energy (anaemia).

Calcium: Cheese, milk, green veg. Strengthens bones and teeth. Weak brittle bones/teeth (rickets), muscle weaknesses and cramps.

What is the general use of fibre from our diet?

Provides something for the gut wall to push against, thereby helping the movement of food and stopping constipation. Absorbs poisonous waste from bacteria in the gut.

Sources: cabbage, sweetcorn, celery.

What is batch culture?

Batch culture is fermentation set-up in a closed or batch fermenter. In batch culture fermentation, the bacteria are placed in batches and then they go through all their growth phases. Finally, the fermentation is halted and the product is collected all at once. The cycle is then restarted.

What is continuous culture?

Continuous culture is carried out in an open fermenter. The bacteria/nutrients are inputted continuously and the product is outputted continuously.

How are microorganisms used in yoghurt production?

It uses batch culture. It needs an idea temp of 40 degrees (best temp for bacteria growth). Once the milk is at this temp, the bacteria are added, they respire anaerobically using the milk sugar lactose as their energy source. The end product of this respiration is lactic acid, which lowers the pH of the milk and causes it to coagulate (change into a thickening mass).

Next, it is mixed with fruit for flavourings. Sometimes, it is treated to kill the bacteria, whilst others contain live bacteria that can aid the natural digestive-system-helping bacteria in our guts.

How are microorganisms used in mycoprotein production?

Mycoprotein is a high-protein meat-substitute for vegetarians. It uses continuous culture. A fungus (Fusarium) is supplied with various nutrients (oxygen, glucose (energy), mineral salts and ammonia) for its growth and its temp is kept at the optimum of 30 degrees. The hyphae are processed to give a meat like texture. Flavouring is added so it can be used in burgers, pies, sausages etc. An advantage it has over regular meat is that it is low in fat.

Why are colourings used on food?

When food is processed, much of its original colour is lost, so colourings can be used to replenish it. They can also be used to make sweets and soft drinks bright and colourful in order to increase their appeal.

What are preservatives and anti-oxidants used for?

To protect food from going off (decomposed by bacteria or being oxidised by oxygen), thereby giving it a longer shelf-life, which is beneficial for both shops and customers.

What are flavourings used for?

To reproduce the exact natural flavour of many natural foods. They can identify the main compounds of specific flavours and replicate them. Also, flavour enhancers like MSG can be used to enhance the food's original flavour.

What are emulsifiers and stabilisers used for?

They enable fats and oils to mix with water.

What are the disadvantages of food additives?

Tartrazine (E102) has been linked to asthma and hyperactivity in children and has hence been banned in some countries.

E320 has been linked to cancer.

16: What is inheritance?

The transfer of genetic information from generation to generation.

How are chromosomes, DNA (deoxyribonucleic acid) and genes related?

A chromosome is a thread of DNA made up of genes. There are 46 chromosomes in a human nucleus (diploid). Each gene is a strand of DNA that codes for a specific protein.

What is mitosis?

It is a type of nuclear division that occurs during growth, the daughter cells are genetically identical.

There is a cell with some chromosomes -> the chromosomes replicate and split apart -> the replicates and splits apart.

What is meiosis?

Human sex cells can't have 46 chromosomes each, they need to be haploid so there can be genes from both parents.

Meiosis is a type of nuclear division that occurs for making sex cells. It results in genetic variation.

Double diploid cell (e.g. from testes) -> two diploid cells -> four haploid cells which become sperm cells.

What is an allele?

A different version of the same gene. Most genes have many alleles.

How do the symbols representing different alleles work?

'A' is a dominant gene. 'a' is a recessive allele of this gene. For example, brown eye colour might be 'A', and blue might be 'a', so if one parent has 'A' and the other has 'a' then the child's eye colour will most likely be brown. Recessive is only displayed if no dominant is present. Dominant is always displayed.

What do these words mean:





Genotype: the alleles the organism possesses.

Phenotype: the alleles the organism displays.

Homozygous: the alleles for a characteristic are identical, e.g. AA or tt.

Heterozygous: the alleles for a characteristic are dissimilar, e.g. Aa or Tt.

You can work out the chances of a child inheriting certain characteristics by using a parental cross diagram

T = tall, t = dwarf.

The offspring have a 75% chance of being tall (50% heterozygous tall, 25% homozygous tall) and a 25% chance of being a dwarf.

T = tall, t = dwarf.

The offspring have a 75% chance of being tall (50% heterozygous tall, 25% homozygous tall) and a 25% chance of being a dwarf.

What is co-dominance?

Co-dominance occurs when both parents have equally dominant alleles.  They are both expressed. So for example, the flower to the right is pink because the alleles for red and white are equally dominant.

Co-dominance occurs when both parents have equally dominant alleles. They are both expressed. So for example, the flower to the right is pink because the alleles for red and white are equally dominant.

How does inheritance work with blood type?

The four blood-types are A, B, AB and O. A and B are dominant. These are decided by the alleles Iᴬ, Iᴮ and Iᴼ. Iᴬ and Iᴮ are dominant, if they clash then the blood-type is AB (co-dominance). Iᴼ is recessive, it can only be formed by two Iᴼs.

6: What does chlorophyll do?

Chlorophyll absorbs light energy that is used in photosynthesis.

What is photosynthesis? What is its equation?

Photosynthesis is the process by which plants make glucose from raw materials using energy from light.


6CO2 + 6H2O --> C6H12O6 + 6O2

What are the two raw materials needed for photosynthesis?

Carbon dioxide and water are the raw materials for photosynthesis.

A leaf that has been exposed to light will give a positive test for starch.

sneil the snail™

What are the requirements for photosynthesis?

Plants need light, chlorophyll, carbon dioxide and water in order to carry out photosynthesis.

We can test to see that light, chlorophyll and carbon dioxide are needed for photosynthesis by...

not giving plants each of these and testing leaves for starch.

What are the products of photosynthesis?

Products of photosynthesis include glucose, which is used to make starch, cellulose, amino acids (and then proteins).

Why is photosynthesis important?

Photosynthesis is important as it provides us with food and medicines; it helps to keep constant concentrations of carbon dioxide and oxygen in the atmosphere.

Increasing either light intensity or temperature...

increases the rate of photosynthesis up to a point where some other factor is limiting.

What is a limiting factor?

A limiting factor is something in such short supply that it restricts life processes. Limiting factors of photosynthesis are: light intensity, temperature and carbon dioxide concentration.

Increasing the carbon dioxide concentration...

increases the rate of photosynthesis when no other factor is limiting.

Carbon dioxide concentration, light intensity, humidity and temperature are controlled in modern glasshouse systems to give optimum conditions.

This ensures that the rate of photosynthesis is kept high so plants produce maximum yield.

The diagram of the internal structure of a leaf shows different tissues which each have important functions to carry out.

like dis

like dis

What do stomata do?

Stomata control the diffusion of gases into and out of a leaf.

What do plant roots absorb and why?

Plant roots absorb nutrients including nitrate ions needed for healthy growth.

What are nitrate and magnesium ions used for?

Nitrate ions are needed to make amino acids; magnesium ions are used by the plants to make chlorophyll.

7: Why are saturated fats harmful if consumed too much?

They increase blood cholesterol which is linked to narrowing of the arteries and heart disease.

What causes weight gain?

What causes obesity?

People often gain weight if their energy intake (food) is more than their energy output (exercise).

Obesity can be caused by a high intake of fatty foods and refined foods containing a lot of added sugar, plus the effects of little exercise.

What causes constipation?

lack of fibre

What does starvation result in?

Low body mass with lack of fat and muscle wasting. Plus protein energy malnutrition (PEM), this includes kwashiorkor (belly swells because the body can't process water) or marasmus (looking very thin and sickly)

How has food production increased in modern times?

Improvements in agricultural machinery, chemical (NPK) fertilisers), pesticides for pests, herbicides for weeds, selective breeding and genetic modification of plants.

What can cause famine?

Political issues (such as the Holodomor in the Ukraine), lack of food transport (oh no my ox is broken), drought, flooding, and an ever increasing human population.

just gonna skip all of digestive system cos it's effort and i made a txt summary of it ages ago, flip to see link

What are the uses of incisors, canines, premolars and molars?

Incisors: biting/cutting

Canines: piercing/tearing

Premolars/molars: chewing/grinding

What is tooth decay caused by? How can it be avoided?

Bacteria in plaque, which change sugar to acid that damages the enamel and dentine of teeth.

It can be avoided by avoiding sugary foods, regular brushing and dental appointments.

What is the structure of a tooth like?

each layer gets progressively more sensitive, if decay reaches pulp you will be in agony.

each layer gets progressively more sensitive, if decay reaches pulp you will be in agony.

What is getting added to drinking water for dental reasons? Why is this controversial?

Fluoride, because it reduces the incidence of tooth decay. However, some are against this because the long-term health effects are not known.

What is deamination?

Amino acids cannot be stored so they are broken down instead. One molecule is converted to carbohydrate or fat and used as a source of energy. The other is converted to NH3 which combines with CO2 to form the excretory product urea, which passes out in urine.

The liver also breaks down toxins, such as drugs like alcohol and paracetamol

8: Xylem vessels transport…

water and mineral ions from the roots up the stem to the leaves.

Phloem vessels transport…

Sucrose, made in the leaves during photosynthesis and in storage organs, to other parts of the plant.

Xylem and phloem are distributed in a central core inside a root. Inside a stem they are organised into vascular bundles.


How do roots take up water?

Water enters a root hair cell by osmosis (high water potential to low water potential). It then passes across the cells of the root cortex by osmosis before passing into the xylem and then up the stem to the leaves.

How are root hairs adapted for their purpose?

Root hairs are well adapted for the absorption of water since they have thin cell walls and have a large surface area.

How is water taken up the stem?

Loss of water from the leaves ‘pulls’ more water up the stem from the roots in the transpiration stream. This happens because of cohesion (water molecules' tendency to stick to each other because of their polarity) and adhesion (water molecules' tendency to stick to the walls of the xylem)

What is transpiration?

Transpiration is the evaporation of water at the surfaces of the mesophyll cells followed by the diffusion of water vapour through stomata to the atmosphere.

What happens to plants when water loss is greater than uptake?

They wilt, because of the lack of turgor (turgidity) in cells in stems and leaves.

What are the effects of increased light intensity/ temperature/wind velocity/humidity on the rate of transpiration?

Increased light intensity opens the stomata and increases transpiration rate.

Increasing temperature and wind velocity increase the rate of transpiration.

Increasing humidity decreases the rate.

How are desert plants (Xerophytes) adapted?

Desert plants such as cacti have thick cuticles, leaves reduced to spines, swollen stems to store water and extensive root systems. Often their stomata close during the day and absorb carbon dioxide at night.

How are pond plants (Hydrophytes) adapted?

Pond plants do not need much transport tissue since they are buoyed up in water. They have extensive air spaces to store carbon dioxide and oxygen which diffuse very slowly in water. They have air pockets to keep them afloat.

How are garden plants (Mesophytes) adapted?

Many garden plants do not experience extremes of water supply and subsequently do not have extreme adaptations.

What is translocation?

Translocation is the movement of sucrose and amino acids from the leaves to regions of respiration, growth and storage.

What do systemic pesticides do?

Why are they effective?

Crop plants absorb them. Systemic pesticides are effective since they are translocated around the plant to all the tissues that a pest may attack. (pests will ingest the pesticide with the plant tissue and ded)

What do contact pesticides do?

Kill pests that they are sprayed onto

What is the difference between transpiration and translocation?

Transpiration is a passive process involving dead tissue. Translocation is an active process involving living tissue.

9: What do the heart and valves ensure?

They ensure a one-way flow of blood around the circulatory system.

Humans have double circulation.

They ensure a one-way flow of blood around the circulatory system.


In what order does blood go through the major arteries and veins?

left ventricle -> aorta -> body -> vena cava -> right atrium -> right ventricle -> pulmonary artery -> lungs -> pulmonary vein -> left atrium -> left ventricle -> repeat until kill

left ventricle -> aorta -> body -> vena cava -> right atrium -> right ventricle -> pulmonary artery -> lungs -> pulmonary vein -> left atrium -> left ventricle -> repeat until kill

The heart consists of two muscular pumps divided by a septum. Each side has two chambers: an atrium and a ventricle.


What do the ventricles and valves do?

Ventricles contract to force blood into arteries; valves make sure that blood flows in one direction.

What are the differences between arteries and veins?

Arteries have thick muscular and elastic walls to withstand high blood pressure. Veins have much less muscle and elastic tissue and have thin walls. Blood pressure in veins is low.

Why is the left ventricle more muscular than the right one?

it must pump blood around the whole body, unlike the right ventricle that only has to pump it to the lungs.

What is diastole?

What is systole?

Diastole: when heart muscles are relaxed

Systole: when heart muscles contract

Why do capillaries have one-cell thick walls and lots of surface area?

So that substances can pass easily in and out of the blood in body tissues.

What is the effect of physical activity on pulse rate (in detail)?

Physical activity increases pulse rate, supplying the muscles with more oxygen and glucose and removing carbon dioxide quicker. If it gets too high, there will not be enough oxygen to respire aerobically so anaerobic respiration will be done instead, causing build-up of painful lactic acid that must be removed afterwards by oxygen debt.

What is Coronary Heart Disease (CHD) caused by?

Coronary heart disease is caused by blockage of the coronary arteries that supply the heart with glucose and oxygen.

What are the risk factors of CHD?

Risk factors which we cannot control are genes, age and sex. Avoidable risk factors include diet, stress, lack of exercise and smoking.

What are the main components of blood?

The main components of blood are plasma (55%, water with chemicals in it such as nutrients and hormones), red blood cells (no nuclei, concave, haemoglobin to store oxygen), white blood cells (have nuclei, phagocytes and lymphocytes) and platelets (tiny fragments of cells which cause blood to clot). Red and white blood cells are visible under the light microscope.

What does haemoglobin in red blood cells do?

In the lungs' capillaries, they combine with oxygen to form oxyhaemoglobin.

What do phagocytes do?

They're a type of white blood cell. Phagocytes ingest pathogens and digest them using enzymes.

What do lymphocytes do?

They're a type of white blood cell. Lymphocytes make antibodies that protect against pathogens in the body.

What is immunity?

After a person has had a disease, the lymphocytes remain to produce more antibodies for that pathogen if the disease is encountered again. This is called immunity.

What do platelets do?

Platelets help to convert fibrinogen to fibrin to form a meshwork of fibres during blood clotting (a scab).

When tissue fluid enters the lymph capillaries it is termed…


blood plasma = tissue fluid = lymph, same thing in different places

What does lymph consist of?

Lymph consists of plasma and white blood cells, but has no red blood cells or large plasma proteins.

The lymphatic system has a separate circulation which returns lymph to the blood.


What do lymph nodes contain?

Lymphocytes are in lymph nodes where they multiply during an infection and produce antibodies.

10: What happens in aerobic respiration?

In aerobic respiration, glucose is broken down to release energy in the presence of oxygen, forming carbon dioxide and water.

What happens in anaerobic respiration?

In anaerobic respiration, glucose is broken down to release energy in the absence of oxygen, forming lactic acid in muscle tissue, or alcohol plus carbon dioxide in yeast and plants.

Which releases more energy: aerobic or anaerobic?

Far more energy is released from each molecule of glucose in aerobic than in anaerobic respiration.

Where does inspired air enter?

Inspired air enters the larynx, which also contains the vocal chords.

Where does the inspired air travel?

The inspired air passes down the trachea, bronchi, and bronchioles to the alveoli.

Where does gas exchange occur?

Gas exchange occurs between the air in the alveoli and the blood in the surrounding capillaries.

How are gas exchange surfaces such as alveoli adapted?

Gas exchange surfaces are moist (oxygen can dissolve into the water lining in the alveolus and then diffuse through the capillary wall into the blood) , thin, have a large surface area and a good blood supply.

How do inspiration and expiration occur?

Inspiration: ribs move up and out, external intercostal muscles contract, diaphragm contracts and moves down

Expiration: ribs move down and in, external intercostal muscles relax, diaphragm relaxes and moves up

How are dust particles and pathogens removed?

Mucus in the trachea, bronchi and bronchioles trap dust particles and pathogens in the air and cilia beat to carry a stream of mucus up to your nose and throat for you to swallow.

What triggers changes in breathing?

An increase in the concentration of carbon dioxide and a lowering of pH in the blood reaching the brain triggers these changes in breathing.

In the absence of oxygen, yeast and exercising muscles carry out anaerobic respiration.


What does a build-up of lactic acid produce?

The build-up of lactic acid in muscles during hard exercise produces an oxygen debt that has to be paid back by breathing in extra oxygen.

Why is anaerobic respiration of yeast important?

Anaerobic respiration of yeast has an important role to play in both brewing and bread-making.

11: What is homeostasis?

Homeostasis is the maintenance of constant internal conditions, such as body temperature.

What is negative feedback?

Homeostasis involves negative feedback. Negative feedback involves reacting to quantities of a substance being too large or too small. It operates to maintain constant conditions of glucose, water, carbon dioxide and oxygen in the blood as well as its pH.

What does the pancreas do?

The pancreas controls the concentration of glucose in the blood by producing the hormones insulin and glucagon which stimulate the liver.

Glucagon turns glycogen into glucose (glu-gly-glu)

Insulin does the opposite

How is body temperature controlled?

Body temperature is monitored and controlled by the hypothalamus in the brain.

What helps control temperature?

Hairs, sweat glands, temperature receptors, blood vessels and fat tissue help control temperature.

What processes help control temperature?

Temperature receptors, insulation, erect/limp body hairs (goosebumps), sweating, shivering, vasodilation and vasoconstriction of arterioles all help to maintain a constant body temperature.

What is excretion?

Excretion is the removal from the body of waste chemicals made in tissues during metabolism.

What are examples of excretory products?

Excretory products include carbon dioxide and urea.

What do the kidneys do?

The kidneys filter materials out of the blood, take back useful substances into the blood, e.g. glucose, control the quantity of water lost in the urine and excrete urea in the urine.

How does the blood that the kidney works upon come and go?

Comes from the renal artery, leaves from the renal vein.

What does the renal (bowman’s) capsule do?

The renal capsule filters the blood removing urea, salts, glucose and water from the glomerulus.

What is reabsorbed into the blood after it's been taken in by the kidneys? How does this happen?

Useful things like some salts, water and glucose.

They are reabsorbed from the blood in the kidney tubules by capillaries that are wrapped around them.

Where does urine travel?

Urine, consisting of urea, some salts and most of the water passes out of the kidneys, along the ureters, to be stored in the bladder until urination.

What does a dialysis membrane do?

A dialysis membrane allows small molecules to pass through pores but prevents large molecule from diffusing through.

What happens during kidney dialysis?

During kidney dialysis urea and some salts pass out of the blood into the dialysis fluid. There is no net diffusion of glucose, since it is in the same conc in the blood and the dialysis fluid.

During kidney dialysis urea and some salts pass out of the blood into the dialysis fluid. There is no net diffusion of glucose, since it is in the same conc in the blood and the dialysis fluid.

What are the advantages/disadvantages of kidney transplants?

Kidney transplants avoid the inconvenience of dialysis, but there may be problems in finding a suitable donor and there is always the risk of tissue rejection.

12: What is the human nervous system made of?

The human nervous system is made up of the central nervous system (brain and spinal cord) and the peripheral nervous system (cranial and spinal nerves).

What do neurones transmit?

Neurones or nerve cells transmit nerve impulses.

What are the two types of actions?

Some actions are involuntary (not under conscious control). Other actions are voluntary and involve conscious control by the brain.

What is a reflex arc?

A reflex arc is made up of three types of neurone: a sensory neurone, a relay neurone and a motor neurone.

What is the nature of reflex actions?

Reflex actions are rapid, automatic and often protective.

What are antagonistic pairs of muscles?

Antagonistic pairs of muscles bring about movement at joints; when one muscle contracts, the other muscle relaxes.

What are sense organs?

Sense organs are groups of receptor cells that respond to specific stimuli: light, sound, touch, temperature and chemicals.

What is the insulation of the neurones?

myelin, a layer of fat.

What happens when two neurones meet?

There is a small gap between them called a synapse. When an impulse reaches a synapse a 'chemical transmitter substance' is released from the first neurone which diffuses across the synapse to reach the second neurone and trigger an impulse.

What are the main three types of neurone and how can you distinguish them?

Sensory neurones have one end in a sensory organ and one end in the central nervous system (within the spinal cord), with cells attached perpendicularly along the way.

Motor neurones have one end in an effector muscle and one in the central nervous system.

Relay neurones are the intermediary between these two within the central nervous system.

Describe a reflex arc.

a finger touches a pin (the stimulus) -> this is detected by the receptors in the skin which generate an impulse -> this impulse travels along a sensory neurone to the spinal cord -> inside the grey matter in the spinal cord the impulse passes across a synapse to a relay neurone and then across a second synapse to a motor neurone -> the motor neurone transmits the impulse to a muscle in the arm -> the muscle (the effector) contracts and causes the arm to move away from the pin (the response)

What does the pupil reflex involve?

The pupil reflex involves the coordination of radial muscles and circular muscles in the iris to control the intensity of light entering the eye through the pupil.

What is involved in accommodation?

The ciliary muscles, suspensory ligaments and the lens are all involved in accommodation (focusing) in the eye (stretching and squashing the lens to focus on things).

What are rod and cone cells?

In the retina, rod cells are distributed around the periphery and respond to light of low intensity. Cone cells respond to high light intensity and detect colour. The fovea is made entirely of cones.

What are hormones?

Hormones are chemicals, produced by endocrine glands that circulate through the blood and alter the activity of target organs.

What does adrenaline do?

Adrenaline stimulates the liver, heart, lungs and arterioles in muscles and gut during stress and emergencies.

What is bovine somatotropin?

Bovine somatotropin is a hormone that is used to increase milk production in cattle. A controversy with it is that it can cause inflammation of udders.

What is a geotropism?

A geotropism is a growth response to the stimulus of gravity. Roots are positively geotropic and shoots are negatively geotropic.

What is a phototropism?

A phototropism is a growth response to the stimulus of light. Shoots are positively phototropic and grow towards the light.

What are auxins?

Auxins are plant hormones that control growth. Synthetic auxins are used as weed-killers by making the weeds grow too fast.

In roots, auxins discourage growth, they build up on the lower side of a root so it bends downwards into the ground.

In stems, they encourage growth, they build up on the side in the shade and cause the stem to bend to the sun.

13: What is a drug?

A drug is a substance taken into the body, which alters or influences chemical reactions in the body.

What do antibiotics do?

Antibiotics destroy pathogens by disrupting cell wall formation, inhibiting protein synthesis and metabolism in the pathogen cell.

Why can antibiotics not kill viruses?

Antibiotics cannot kill viruses since they have no cell wall and live inside host cells, taking over their metabolic processes.

What is heroin?

Heroin is a highly addictive depressant. While the user experiences a feeling of euphoria, tolerance and dependence develop, resulting in addiction.

What are problems associated with heroin?

What are problems associated with heroin?Heroin addicts may turn to crime to obtain money for their next dose. Shared needles have resulted in the spread of hepatitis and HIV amongst addicts who inject heroin.

What is alcohol?

Alcohol is a depressant and if taken in excess, it can worsen reaction times and bring about a lack of self-control in a person.

What are the long-term effects of alcohol?

Long-term effects of alcohol abuse include cirrhosis of the liver (liver full of nodules and unable to function properly) and brain damage.

What is in tobacco smoke?

Tobacco smoke consists of nicotine, tar, carbon monoxide and smoke particles.

What diseases are associated with smoking?

Smoking is associated with diseases such as bronchitis, emphysema, heart disease and lung cancer.

18: What source do all organisms in all ecosystems take from?

the sun






habitat: place where an organism lives

population: group of organisms of the same species living in the same habitat at the same time

community: all the populations of all the species in an area

ecosystem: the community and all the physical factors that influence it.

What are food chains and food webs?

Food chains show a single flow of food and energy between different trophic levels in a community.

Food webs show the interconnecting food chains within a community.

What are pyramids of numbers and pyramids of biomass?

Pyramids of numbers show how many individuals there are at each trophic level, but give no indication of their size.

Pyramids of biomass indicate the mass of living material at each trophic level, but give no indication of the rate of growth.

How is energy lost between each trophic level of the food chain?

about 90% is lost for each level due to respiration and waste materials.

How can humans receive more energy from food chains?

By feeding as primary consumers rather than secondary ones. For this reason, a vegetarian diet can support far more people than one based on meat products.

Describe the carbon cycle.

Describe the water cycle.

energy from the sun powers the water cycle.

water evaporates from the sea --> becomes clouds --> gets colder as clouds rise, they condense and it rains --> (animals breathe out water vapour) --> (some water evaporates from the soil, some water transpirates from trees) --> water returns to sea via rivers, streams and underground water

How do decomposers assist in cycling nutrients through the ecosystem?

nitrogen cycle

is complicated so you should just read the textbook pages

19: Why does a population increase or decrease?

Due to deaths, births, immigration and emigration.

What factors affect the growth and final size of a population?

food availability (competition for resources), predation and disease.

What are the four phases of bacteria growth?

Lag phase: where the bacteria doubling in number makes little difference because there are so few

Exponential: where the doubling starts to make a difference and the growth is exponential

Stationary: where the bacteria are dying at the same rate they're producing, maybe because of food shortages or built-up waste products

Death: maybe cos of toxic waste products, food shortages or oxygen shortage

What factors have caused the exponential growth in the human population? How have they caused this?

improved agriculture, public health (sanitation, water supplies etc.) and health care caused the growth by decreasing infant mortality rates and death rates and increasing life expectancy.

What are the implications and issues of increased human population?

higher demand in food supplies, energy, housing and space to dump rubbish

What are the causes and implications of deforestation?

Deforestation is due to the world demand for timber and and paper. Land is also cleared for farms, cattle and new roads.

It causes soil erosion, severe storms, flooding, the destruction of habitats and extinction of species.

Give some examples of non-renewable and renewable sources.

non-renewable: fossil fuels and minerals (e.g. copper, zinc and lead ores). Once gone they cannot be replaced

renewable: timber and fish/molluscs from the sea and lakes. They can be replaced as fast as they are taken.

What effect do rainforests have on maintaining levels of carbon dioxide and oxygen in the atmosphere?

What ecosystems absorb carbon dioxide from the atmosphere? How?

Rainforests have no effect, they give out as much CO2 as they absorb in photosynthesis, and the oxygen they produce is negligible.

However, some forests and peat bogs in northern latitudes can act as 'carbon sinks': long-lived plants store carbon, and when they die they don't decompose much so they form peats of dead vegetation that 'lock up' carbon for a long time.

What is pollution? Give some examples.

The harm done to the environment by the release of substances from human activities.

Examples: CO2 and SO2 (from fossil fuels), sewage, methane (paddy fields and cattle), herbi/pesticides, non-biodegradable plastics (packaging), nuclear fallout (atom bombs, power station accidents etc.)

What is nuclear fallout?

Nuclear radiation from our surroundings. It usually isn't an issue, but when human-caused disasters occur, such as atom bombs and nuclear power station accidents, it can be. This is because they release high quantities of radioactive substances with long half-lives. Radiation poisoning can cause: death, sickness, loss of hair, cancer and mutations that may be inherited for generations.

There are biodegradable and non-biodegradable plastics.


some biodegradable plastics have starch incorporated into them so they can be digested by bacteria.

What is the greenhouse effect and what issues will it cause?

UV radiation comes in, warms up earth, turns into infra-red radiation, trys to leave earth, can't cos of greenhouse gases like CO2 and methane, sticks around and warms up earth some more.

Leads to rising sea levels, flooding of low-lying areas, more extreme weather, less crop produciton

What is acid rain and what issues does it cause?

When coal is burnt, the sulphur impurities react with oxygen to form sulphur dioxide which escapes into the atmosphere. This then reacts with the air to form sulphur trioxide, and then reacts with water vapour (like in clouds) to form sulphuric acid.

This kills trees and fish, corrodes metals and limestone buildings and acidifies soils.

Can be prevented by flue gas desulphurisation, low sulfur fuels, catalytic converters

Give some examples of water pollutants.

In many parts of the world raw sewage and fertilisers are dumped straight into rivers. Other water pollutants are toxic metals and pesticides.

What is eutrophication?

Excess fertilisers being 'leached' causes eutrophication by supplying algae with nutrients.

algae grow lots --> animals that eat algae cannot multiply fast enough to control their growth --> algae covers surface layers of water, thus reducing light for plants at the bottom --> those plants die and rot --> algae also die as there is so much competition for resources --> decomposing bacteria feed on dead plants/algae --> they aerobically respire and use up lots of oxygen --> fish have less oxygen and die

How do pesticides effect food chains?

Bioaccumulation. If one animals consumes some pesticide, then the animal that eats that animal will also have some, this builds up along the food chain until the higher animals have a lot of pesticide within them and this causes health issues.

Why should animals/plants be conserved?

ecosystems provide us with services such as: treating waste; providing food, fuels and medicine and areas of recreation

maintain balance of life on the planet e.g. thru nutrient cycles

species keep other species in check, so we are not overrun with pests and diseases etc.

stewardship - we have a moral obligation as 'guardians of the planet' ayylmao

How can plants/animals be conserved?

National Parks - protected zones set aside for wild life

Marine parks - like national parks but marine

Rescuing endangered animals/plants, breeding them and then releasing them back into the wild

Reducing habitat destruction e.g. requiring licenses for logging or just preventing it all together

Reducing trade in endangered species e.g. by banning poaching and other blackmarket practices like superstitious Chinese medicines

Sustainable management of ecosystems, e.g. planting as many trees as you cut down

Seed banks - storing seeds for emergencies

How is sewage treated?

Primary treatment: Removing large solids like twigs and paper by filters and screens, then the grit and other things are allowed to settle out in settlement tanks

Secondary: Microbes (mainly bacteria) decomposing materials suspended in water by the activated sludge process and trickle filters. Aerated to break down things like carbohydrates and fats into carbon dioxide.

Tertiary: Sludge comes out and is either used as a starter culture for secondary treatment or is broken down by bacteria into methane which is used to fuel the sewage work's machinery. Otherwise, after further treatment, is disposed in sea or spread over land for plants.

Why do we recycle? How?

To stop pollutants that may harm animals, plants or ourselves. Dumping in landfill sites may take habitats away from plants and animals. To save money, since making goods from recycled materials is much cheaper, easier and takes less materials from the environment.