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88 Cards in this Set
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- Back
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Name 5 parts of a cell which both plant and animal cells have What are their uses? |
Cell membrane - holds the cell together and controls what goes in and out Cytoplasm - Most chemical reactions happen here. Contains enzymes which control these reactions Nucleus - Genetic material Mitochondria - Reactions for respiration / releases energy Ribosomes - Proteins made here
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Name 3 features of a yeast cell |
It is single celled Yeast is a microorganism Contains a nucleus, cytoplasm and a cell membrane surrounded by a cell wall |
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Where is the genetic material found in bacterial cells? Where is the genetic material found in animal cells? |
Bacterial: Cytoplasm - no nucleus Animal: Nucleus |
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Define diffusion |
The spreading out of particles from an area of high concentration to an area of low concentration |
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Name three substances that can diffuse through cell membranes, and two that cant Very briefly, explain why |
Can: Glucose, amino acids, water, oxygen Cant: Starch and proteins
Only small molecules can diffuse through the membrane |
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Which leaf cells are specialised for photosynthesis? How? |
Palisade leaf cells They are packed with chloroplasts, more of them are crammed at the top so they're nearer the light. Tall shape - large surface area Thin shape - pack loads on top of a leaf |
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Give one way that a guard cell is adapted for controlling water loss |
When the plant is short of water, the guard cells lose water and become flaccid, making the stomata (pores) close. |
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How are red blood cells adapted to carrying oxygen? |
Concave shape - big surface area for absorbing oxygen. Helps them pass smoothly through capillaries to reach body cells Packed with haemoglobin - the pigment that absorbs oxygen. No nucleus, more room for haemoglobin. |
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Give three ways that a sperm is adapted for swimming to an egg cell |
Long tail & streamlined head Lots of mitochondria Lots of enzymes (to digest through egg membrane) |
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What is a tissue? What is an organ? |
A tissue is a group of similar cells that work together to carry out a particular function. An organ is a group of different tissues that work together to perform a certain function.
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Provide 3 examples of tissues & uses
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Muscular tissue - contracts the move whatever it's attached to. Glandular tissue - makes & secretes chemicals like enzymes & hormones. Epithelial tissue- covers some parts of the body e.g. inside of the gut. |
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Provide an example of an organ, with its tissues & their uses |
STOMACH Muscular tissue - moves stomach wall to churn up food Glandular tissue - makes digestive juices Epithelial - covers insider & outside of stomach |
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Name one organ system found in the body |
Digestive system |
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Give 3 examples of plant tissues, with their uses
Give examples of plant organs |
Mesophyll tissue - photosynthesis occurs here Xylem & phloem - transport things like water, minerals and ions around the plant Epidermal tissue - this covers the whole plant
Organs - stem, roots, leaves |
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Word and balanced symbol equation for photosynthesis |
Carbon dioxide + water -> (sunlight+chlorophyll above arrow) glucose + oxygen
6CO2 + 6H20 = C6H12O6 + 602
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What is the green substance in leaves that absorbs sunlight? What does it do with the sunlight? |
Chlorophyll It absorbs sunlight and uses its energy to convert carbon dioxide (from the air) and water (from the soil) into glucose. Oxygen is also produced in the process. |
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Name 3 factors that can limit the rate of photosynthesis |
Light Temperature Carbon dioxide/ CO2 |
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Why is it important that a plant doesn't get too got? |
The enzymes which the plant needs for photosynthesis with be damaged/denature. |
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Name 5 ways in which plants use glucose |
Respiration Making cell walls Making proteins Stored in seeds Stored as starch |
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Explain why glucose is turned into starch if plants need to store it for later? |
It is needed when photosynthesis isn't happening, like in the winter Starch is insoluble which makes it much better for storing than glucose - a cell with lots of glucose would draw in loads of water and swell up |
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What is a habitat? What is distribution? |
Where an organism lives The distribution of an organism is where an organism is found |
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Give 5 environmental factors that can affect the distribution of organisms |
Temperature Availability of water Availability of oxygen and carbon dioxide Availability of nutrients Amount of light |
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How do you work out the population size? - distribution of organisms
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Multiply the mean by the total area of the habitat |
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What can a transect be used for? |
Mark out a line, collect data along the line |
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What is a catalyst?
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A substance that increases the rate of a chemical reaction without itself being changed or used up in the reaction
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What is an enzyme?
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They need the right conditions to work properly - temperature and pH |
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What happens to an enzyme as the temperature increases?
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A higher temp increases the rate of reaction at first But if it gets too hot, some of the bonds holding the enzyme together break - this destroys the enzymes active site. This means that it has denatured |
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What is the optimum temperature for enzymes in the human body
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37 degrees Celsius |
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What do enzymes break down in the digestive system?
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The bigger molecules are - starch, proteins and fats The smaller molecules are - sugars, amino acids, glycerol and fatty acids |
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Amylase What it converts Where it is found |
The salivary glands The pancreas The small intestine |
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Protease What it converts Where it is found |
Stomach (its called pepsin in there) Pancreas Small intestine |
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What it converts Where it is found |
The pancreas The small intestine |
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What it does Where it is found |
Hydrochloric acid in stomach makes pH too acidic for enzymes, bile is alkaline Emulsifies fats: Breaks fat into tiny droplets, bigger surface area of fat for lipase to work on - faster digestion Produced in the liver, stored in gall bladder, released in small intestine |
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Salivary glands - what do they do? |
Produce amylase enzyme in the saliva |
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Digestive system Stomach - what does it do? |
Produces protease enzyme, pepsin Produces hydrochloric acid to kill bacteria & to give the right pH for the protease enzyme to work |
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Digestive system Liver - what does it do? |
Neutralises stomach acid Emulsifies fats |
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Digestive system Gall bladder - what does it do? |
Where bile is stored |
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Pancreas - what does it do? |
Releases these into the small intestine |
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Digestive system Large intestine - what does it do? |
Where excess water is absorbed from the food |
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Small intestine - what does it do? |
Digested food is absorbed out of the digestive system and into the blood |
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What is respiration? |
The process of releasing energy from glucose, which goes on in every cell |
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What is the difference between aerobic and anaerobic respiration?
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Aerobic respiration uses oxygen, anaerobic respiration does not. |
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Where does most of the reactions in aerobic respiration occur? |
Inside the mitochondria of plant and animal cells. |
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What is the word equation for aerobic respiration? |
Glucose + oxygen = carbon dioxide + water + ENERGY |
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Give four examples of what the energy released by aerobic respiration is used for
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1 - to build up larger molecules from smaller ones (like proteins from amino acids) 2 - In animals, to allow the muscles to contracts (which then allows them to move about) 3 - In mammals and birds the energy is used to keep their body temperature steady 4 - In plants, to build sugars, nitrates and other nutrients into amino acids, which are then built up into proteins |
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What does physical activity do?
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Increases the speed at which the heart pumps |
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What does an increase in muscle activity require?
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Extra carbon dioxide needs to be removed from the muscle cells. For this to happen blood has to flow at a faster rate |
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What is some of the glucose from food stored as? |
Glycogen |
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Where is glycogen stored? |
Mainly in the liver, but each muscle also has its own store |
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What is glycogen used for? |
During vigorous exercise muscles use glucose rapidly, so some of the stored glycogen is converted back to glucose to provide more energy. |
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What is it? |
It is the incomplete breakdown of glucose, which produces lactic acid |
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What is the word equation for anaerobic respiration?
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glucose = energy + lactic acid |
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What are some disadvantages of aerobic respiration? |
It causes muscle fatigue - the muscles get tired and stop contracting efficiently It does not release nearly as much energy as aerobic respiration - but it's useful in emergencies |
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What is an advantage of anaerobic respiration?
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You can keep on using your muscles for a while longer |
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What does anaerobic respiration lead to?
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Oxygen debt |
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What is oxygen debt?
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What do you do when oxygen debt occurs? |
Blood flows through your muscles to remove the lactic acid by oxidising it to harmless CO2 and water. |
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Which enzymes are used in biological detergents?
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Protein digesting enzymes - proteases Fat digesting enzymes - lipases |
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What are some advantages of using enzymes in industry?
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2 - Using lower temps and pressures means a lower cost as it saves energy 3 - Work for a long time, after initial cost, can continually use them 4 - Biodegradable, therefore cause less environmental pollution |
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What are some disadvantages of using enzymes in industry?
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2 - Enzymes can denature even in a small increase in temp 3 - Susceptible to poisons and changes in pH - conditions must be tightly controlled 4 - Can be expensive to produce 5 - Contamination can affect the reaction |
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What are chromosomes?
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Long molecules of DNA |
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What is a gene?
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A section of DNA, it contains the instructions to make a specific protein. They tell cells what order to put the amino acids together. |
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What are amino acids used for (in DNA)? |
Only 20 amino acids are used, but they make up thousands of different proteins |
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What does mitosis make? |
New cells for growth and repair |
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What is mitosis? |
When a cell reproduces itself by splitting to form two identical offspring. |
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Describe the process of mitosis |
Chromosomes line up at the centre of the cell and cell fibres pull them apart. Membranes form around each of the sets of chromosomes - these become the nuclei of the two new cells Then the cytoplasm divides |
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What is meiosis?
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It produces cells which have half the normal number of chromosomes - gametes. |
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Describe the process of meiosis
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Chromosome pairs line up in the centre of the cell in the first division The pairs are pulled apart In the second division, the chromosomes line up in the centre of the cell again, and the arms of the chromosomes are pulled apart. |
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What is differentiation? |
The process which cells become specialised for a particular job. |
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What is a stem cell? |
They are found in early human embryos |
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Give a possible use of stem cells
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Curing diseases - replacing faulty old ones with new cells with their own functions |
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Why are some people against stem cell research? |
Curing patients who already exist and are suffering is more important |
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What about the other pair? |
The 23rd pair are labelled XX or XY - they decide your gender |
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What chromosomes do men and women have? |
Women - XX |
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What were Gregor Mendel's three conclusions? |
Hereditary units are passed on from both parents, one unit from each plant Hereditary units can be dominant or recessive |
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What are alleles? |
Different versions of genes |
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What is homozygous?
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When an organism has two alleles of a particular gene the same |
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What is heterozygous?
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If an organisms two alleles for a particular gene are different |
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What is a dominant allele? |
If the gene is heterozygous, it is the allele which is expressed
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What are genotypes and phenotypes?
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Phenotype means the actual characteristic |
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What type of allele is cystic fibrosis caused by? |
A recessive one |
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What type of allele is polydactyly caused by? |
A dominant one |
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Briefly tell me what genetic screening is?
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A cell from an embryo is removed, and the genes are analysed. Many genetic orders can be detected in this way Embryos with good alleles would be implanted into the mother - the ones with bad alleles are destroyed |
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Give 4 points against genetic/embryonic screening
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The rejected embryos are destroyed - they could have developed into humans It implies that people with genetic problems are 'undesirable' - could increase prejudice Screening is expensive |
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Give 3 points for genetic/embryonic screening
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There are laws to stop it from going too far Treating disorders costs the government (and tax payers) a lot of money. |
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Give 3 ways which fossils form in rocks |
From casts and impressions From preservation in places where no decay happens |
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Give 6 reasons as to why species become extinct
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A new predator kills them all A new disease kills them all They cant compete with another species for food A catastrophic even kills them all A new species develops |
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What is isolation?
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