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145 Cards in this Set

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Name 10 things found in Eukaryotic Cells?

Nucleus, Nucleolus, Centrioles, Ribosome, Lysosome, Smooth Endoplasmic Reticulum, Rough Endoplastic Reticulum, Golgi Apparatus, Mitochondiron (also vesicles).

Describe the appearance of Mitochondria (2)

- Double membrane with structures inside called cristae.


- Inside the cristae there's the matrix which contains enzymes involved in respiration.

Function of: Nucleus (2)

- Pores that allow substances to move between the nucleus and cytoplasm.


- The nucleolus contains ribosomes.

Function of: Lysosomes (2)

- Contains digestive enzymes


- Used to break down invading cells or to break down worn out components.

Function of: Vesicles

Transports substances in and out of the cell.

Function of: Ribsomes

The site where proteins are made.

Function of: Smooth Endoplasmic Reticulum

Synthesises and processes lipids.

Function of: Rough Endoplasmic Reticulum

Folds and processes proteins that have been made at the ribosome.

Function of: Golgi Apparatus (2)

- Processes and packages new lipids and proteins.


- Creates lysosomes.

Function of: Centrioles

Involved with the separation of chromosomes during cell division.

Function of: Mitochondrion (2)

- The site of aerobic respiration.


- Where ATP is found.

What is a micrometre?

0.001mm

Name 6 things found in a prokaryotic cell?

DNA, cell membrane, flagellum, ribosomes, plasmids, cell wall/capsule.

Differences between pro and eukaryotic cells? (6)

- E are larger cell.


- E has linear DNA, P has circular.


- E has a nucleus, P has DNA free in cyto.


- E have no cell wall, P have polysaccharide walls.


- E have many organelles and mitochondria, P have fewer and no mitochondria.


-E have larger ribosomes.

What causes a reduction in global biodiversity? (2)

- The extinction of a species.


- Loss of genetic diversity.

Why are some species at risk of extinction?

Low populations or threatened habitats.

What does conservation involve?

The protection and management of endangered species.

What do zoos and seedbanks do?

Help to conserve endangered species and conserve genetic diversity.

What do seedbanks do? Why?

Store lots of seeds from different species, to conserve biodiversity by storing endangered plants.

How do seed banks help conserve plants?

New plants can be grown if they become extinct in the wild.

How do seed banks help conserve genetic diversity?

They store a range of seeds with different characteristics/alleles.

What does the work of seed banks involve? (2)

- Cool, dry conditions are made so they can be stored for a long time.


- Seeds are tested for viability, planted, grown and new seeds harvested.

Advantages of seedbanks. (5)

- Cheaper than storing plants.


- Large no. stored in small spaces.


- Less labour.


- Stored anywhere as long as cool and dry.


- Less likely to be damaged by disease/natural disaster.

Disadvantages of seedbanks. (3)

- Testing viability is expensive and time-consuming.


- Too expensive to store all seed types.


- Difficult to collect seeds from remote locations.

What programs do zoos have to help endangered species?

Captive Breeding Programmes

What do captive breeding programmes involve? (2)

- Species that are endangered/already extinct can be bred to increase no.


- Kept in controlled environments.

What can zoos and seedbanks do to help keep up animal and plant numbers?

Reintroduce into the wild.

How does reintroduction help other organisms and environments? (2)

- Restore habitats


- Help organisms that need food/increase no.

What problems does reintroduction cause? (2)

- May bring new disease.


- Might not have the same behavioural traits (may have difficultly finding food/mates).

What are the issues with captive breeding programmes? (2)

- Have problems breeding outside their natural habitat.


- Its cruel to keep animals in captivity.

How do seedbanks contribute to scientific research? (3)

- Useful for reintroduction.


- Used for medical research or new materials.


- Disadvantage - limits data to small interbred populations.

How do zoos contribute to scientific research? (3)

- Increases knowledge about behavioural, physiological and nutrional needs of animals. Contributes to conservation efforts.


- Research can happen that isn't possible in the wild.


- Disad - captive animals act differently.

How do zoos and seedbanks help educate people about conservation? (2)

- Increases enthusiasm for conservation work, as you get close to animals.


- Educates and provides training/jobs.

What is biodiversity? (3)

- The variety of living organisms in an area like:


- Species diversity (the no. of diff species and their abundance).


- Genetic diversity (the variation of alleles in a species).

What helps maintain biodiversity?

Conservation

What is endemism?

When a species in unique to a single place.

What is species richness?

The number of different species in the area.

What is genetic diversity?

The variation of alleles in the gene pool.


What 2 things can you use to measure genetic diversity of a species?

Phenotype and Genotype.

What is a gene pool?

The complete set of alleles in a species or population.

Phenotype (2)

- The observable characteristics of an organism.


- Different alleles code for a different version of the same gene.

What was the old method for testing drugs?

Trial and error - chance observations.

What is modern drug testing like?

More controlled and a rigorous process.

What happens before live subjects are used in drug testing? (2)

- Computer model potential effects.


- Tests carried out on human tissue and live animals.

How many phrases of drug testing is there?

3 phrases of clinical trials.

Describe the phrases of testing during clinical trials? (3)

1) Tested on a small group of HEALTHY individuals. To find safe dosage/side effects/how the body reacts.


2) Tested on a larger group of patients.


3) Drug compared with existing treatment on 100s/1000s of patients. Half with new drug, half with old.

What 2 techniques can make a study more reliable?

Using placebos and a double blind trial.

Placebos (3)

- A placebo is an inactive substance that looks like the drug but doesn't do anything.


- Patients can undergo the placebo effect - where they show improvements because they think it's a working treatment.


- Allows researchers to know if the drug improves health more than the placebo.

Double blind trials (2)

- Neither the patient nor the doctors know who's been given the new drug or old drug/placebo.


- This reduces bias in results as attitudes can't affect the outcome.

What is sustainability?

Using resources to meet the need of the present generation, without using too much that the future generations supply is gone.

How can you make products sustainable?

Renewable resources.

Examples of sustainable and unsustainable practises?

- Replacing trees after logging.


- Using fossil fuels.

Using plant fibres to contribute to sustainability? (4)

- Ropes/fabrics can be made from plastic or plant fibres.


- Plant fibres = more sustainable, crops can be regrown.


- They're biodegradable.


- Easier to grow and process than oil extraction.

Using starch to contribute to sustainability? (3)

- Can be used to make bioplastics.


- More sustainable/can be regrown.


- Can be used to make bioethanol/biofuels.

What do plants need?

Water, minerals and sunlight.

What happens if plants have little minerals?

The plant will suffer deficiency symptoms like stunted growth.

What 4 things do plants need - why? (8)

- WATER; photosynthesis, maintain structural rigidity, transport minerals and regulate temp.


- MG IONS; the production of chlorophyll (the pigment needed in photosynthesis).


- NITRATE IONS; for the production of DNA, proteins and chlorophyll. Required for plant growth, fruit/seed production.


CA IONS; component in cell walls, needed for plant growth.

What is celluloses main function?

The main component in cell walls.

Describe celluloses structure? (5)

- Long, unbranched chains of b-glucose.


- Joined by straight glycosidic bonds.


- Between 50 and 80 cellulose chains are linked together by a large no. of H bonds.


- This forms strong threads called microfibrils.


-This gives the cell wall structural support.

Why is cellulose strong? (4)

- Cellulose microfibrils in a net-like cross arrangement gives it strength.


- Some structural plant cells (like sclerenchyma) produce a second cell wall between the primary wall and cell membrane.


- The secondary wall is thicker, with more lignin - this makes it stronger.


- The growth of the secondary wall is called the secondary thickening.

Define tensile strength?

The maximum load a fibre can take before it breaks.

Name 7 plant organelles?

Cell wall, middle lamella, plasmodesmata, pits, chloroplast, amyloplast, vacuole and tonoplast.

What is the middle lamella? What does it do?

The outer most layer of the cell.


Acts as an adhesive and sticks together adjacent cells. Stability.

What is the plasmodesmata? What does it do?

Channels in the cell wall that links adjacent cells.


Allows transport and communication between.

What are pits? What do they do?

Thin regions in the cell wall.


Allow transport of subs between cells.

What do chloroplasts do?

Its the site where photosynthesis occurs.

What do amyloplasts do?

Storage of starch grains to convert to glucose when needed for energy.

What does the vacuole and tonoplast do?

The vacuole contains cell sap.


It keeps the cell turgid and the tonoplast controls movement of subs into/out the vacuole.

What are the two parts of stems you need to know about?

The xylem vessels and sclerenchyma fibres.

What is the function of xylem vessels? (2)

To transport water and mineral ions up the plant.


Provide support.

Describe xylem vessels structure? (4)

- Long, tube-like formed from dead cells joined end to end and found in bundles.


- Longer than they are wide and are hollow tubes with no end walls.


- Walls are thickened with a woody substance called lignin which gives support.


- This creates an interrupted tube.

What do the pits allow on xylem vessels?

Water and mineral ions to move into/out the vessels where there is no lignin (which is waterproof/hydrophobic).

Where are xylem vessels found?

Throughout the plant but mostly around the centre of the stem.

Function of sclerenchyma fibres?

They provide support

Describe sclerenchyma fibres structure? (3)

- Made of bundles of dead cells that run vertically up the stem.


- Cells longer than they are wide with a hollow lumen and no end walls.


- Walls thickened with lignin and MORE CELLULOSE than other plant cells.

Where are sclerenchyma fibres found?

Throughout the stem, but mostly the outer edge.

What does taxonomy involve?

Naming organisms and organising them into groups based off their similarities and differences.

How many levels of taxonomic groups are used in classification?

7

Name the taxonomic groups in order of largest to smallest?

Kingdom, Phylum, Class, Order, Family, Genus, Species (King Phillip Can Order Fresh Giant Squid).

Define species.

A group of similar organisms able to reproduce to give fertile offspring.

How are species named?

Genus species

Molecular Phylogeny? (3)

- Phylogeny is the study of the evolutionary history of groups of organisms.


- It tells us which species are related to which and how closely.


- Molecular phylogeny looks at molecules (DNA) to see how closely related organisms are.

What are the 3 domains?

Bacteria, Archaea and Eukarya

Define niche (2)

The role of a species within its habitat.


Its interactions with other living organisms and the non-living environment.

How many species can occupy a niche?

One

Why does it look like some species occupy the same?

Because they'll have the same prey or a similarity, but they'll be slight differences.

What are adaptations?

Features that increase an organisms chance of surviving.

Animals are adapted for their niche; what are the 3 categories of adaptions?

Behavioural, Physiological, Anatomical

Define behavioural adaptions and give examples.

Ways an organism acts that increases its chances of survival and reproduction.


Eg. mating calls, travelling in packs.

Define physiological adaptions and give examples.

Processes inside an organisms body that increases it's chance of survival.


Eg. Lowering metabolisms to conserve energy.

Define anatomical adaptions and give examples.

Structural features of an organisms body that increase it's chance of survival.


Eg. Wings, Teeth.

How do adaptions become more popular in a species?

Because of evolution by natural selection.

Natural Selection (6)

- Genetic variation/variation due to mutation in the population.


- Some individuals possess an advantageous characteristic.


- Therefore more likely to survive to adulthood and breed.


- Advantageous allele passed onto offspring.


- Change in allele frequency over generations.


- Georgraphical/reproductive isolation.

What are the two types of variation in phenotypes?

Continuous and Discontinuous

What is continuous variation? Give examples?

Individuals within a population vary within a range (no distinct categories).


Height, mass, skin colour.

What is discontinuous variation? Give examples?

Two or more distinct categories, each individual falls into only one.


Blood group, sex.

What is different in individuals of the same species?

Different genotype (combination of alleles)

What does variation in genotype result in?

Variation in phenotype (characteristics)



Define monogenic.

Characteristics controlled by one gene.


They show discontinuous variation.

Define polygenic.

Characteristics controlled by a number of genes at different loci.


They show continuous variation.

What is a locus?

The same position on chromosomes where different alleles for the same gene are found.

What are some and most characteristics influenced by?

Most characteristics are influenced by genotype, but some from genotype AND environment.

MAOA (3)

- Enzyme


- Monogenic


- Anti-depressants/smoking reduces levels.

Cancer (2)

- The uncontrolled division of cells that leads to tumours.


- Can be affected by genes or environment.

Hair Colour (2)

- Polygenic


- Environment can affect it - melanin.

What can stem cells develop into?

Any specialised cell type.

Adult stem cells (4)

- Obtained from body tissue (bone marrow)


- Simple op, little risk but uncomfortable.


- Donor under anaesthetic, needle inserted into centre of the bone, a small quantity of bone marrow is removed.


- Can only develop into a range of cells.

Embryonic Stem Cells (4)

- Obtained from early embryos


- Created in a lab via IVF


- Once the embryos are 4-5 days old, stem cells are removed, the embryo is destroyed.


- Can develop into all type of specialised cells.

Ethical issues of embryonic stem cells?

- Destruction of viable embryos is unethical/potential life.

What are stem cells?

Unspecialised cells that can specialise/develop into any type of cell.

What is the process called of stem cells becoming specialised?

They divide by MITOSIS to become new cells which then become specialised.

What is potency?

The ability of stem cells to differentiate into specialised cells.

What is totipotency?

The ability to produce all cell type, including extraembryonic cells.

What is multipotency?

The ability to produce some cell types.

What is pluripotency?

The ability to produced most specialised cells except for extraembryonic cells.

Cell differentiation (5)

- Stem cells all contain the same genes, some are active, others are inactive.


- A chemical stimulus (hormone/signal protein) switches activates the gene.


- mRNA is transcribed from active genes.


- The mRNA from the active gene is then translated into proteins.


- Changes to the cell produced by these proteins cause the cell to become specialised (differentiate).

What is fertilisation?

The fusion of a male and female gamete.

What does fertilisation create?

A zygote cell with the full number of chromosomes (46).

What makes offspring unique?

The combination of genetic material from chromosomes given to the offspring from the two individual parents.

During fertilisation, where are sperm deposited?

High up in the vagina - close to the cervix entrance.

Where does sperm then travel after its deposited?

Up through the cervix and uterus into the oviducts.

Describe the stages of fertilisation (7)

- The sperm swims towards the egg cell in the oviduct.


- When one sperm makes contact with the zona pellucida of the egg cell, the acrosome reaction occurs- digestive enzymes are released from the acrosome of the sperm.


- These enzymes digest the zona pellucida so sperm can move through to the cell membrane of the egg cell.


- The sperm head fuses with the cell membrane of the egg cell. This triggers the cortical reaction. The egg releases the contents of vesicles called cortical granules into the space between the cell membrane and the zona pellucida.


- The chemicals thicken the zona, making it impenetrable to other sperm. This means only one sperm can fertilise the egg.


- Only the sperm nucleus enters the egg cell- the tail is discarded.


- The two gametes fuse.

Fertilisation in plants (7)

- A pollen grain lands on the stigma of a flower, absorbs water then splits open.


- A pollen tube grows out of the pollen grain down the style. There are 3 nuclei in the pollen tube, one tube nucleus and 2 male gamete nuclei.


- The tube nucleus makes enzymes that digest surrounding cells making a way through for the pollen tube.


- When the tube reaches the ovary, it grows through the micropyle (a tiny hole in the ovule wall) and into the embryo sac within the ovule.


- In the embryo sac, the tube nucleus disintegrates and the tip of the pollen tube bursts, releasing the two male nuclei.


- One male nucleus fuses with the egg nucleus to make a zygote which will divide by mitosis to become the embryo of the seed.


- The 2nd male nucleus fuses with the polar nuclei. This produces a food store (endosperm) for the mature seed.

What are gametes, where are they found?

Male and female sex cells.


Found in all organisms that reproduce sexually.

What happens when they join together?

They join together to form a zygote which divides and develops into a new organism.

How are sperm cells specialised to their function? (4)

- Acrosome contains digestive enzymes to break down the eggs cell's zona pellucida and enable sperm to penetrate the egg.

- Nucleus contains genetic info/chromosomes.


- Mitochondria to provide energy for tail movement.


- Flagellum (tail) allows sperm to swim towards the egg cell.




How are egg cells specialised to their function? (2)

- Follicle cells form a protective coating.


- Zona Pellucida forms a protective layer that sperm have to penetrate.

How are gametes formed?

Meiosis

What is meiosis?

A type of cell division that happens in the reproductive organs to produce gametes.

How many chromosomes do cells have before meiosis?

The full set (46)

How does meiosis ensure genetic variation? (2)

- Crossing over of Chromatids


- Independent Assortment of chromosomes

Crossing over of chromatids (5)

- Homologous pairs pair up before division.


- Two chromatids in each pair twist around each other.


- The twisted bits break off their original chromosome and rejoin on the other chromatid, recombining genetic material.


- Chromatids contain the same genes but a different combination of alleles.


- This means 4 new cells formed from meiosis with different alleles.

Independent Assortment of Chromosomes (2)

- All your cells have a combination of different chromosomes from you parents.


- Different combinations of the maternal and paternal chromosomes go into each cell

What is the cell cycle?

The process of cell growth and division

When does the cycle start and end?

Start - when a cell is produced by cell division.


Ends - with the cell dividing to produce two identical cells.

What two periods does the cell cycle consist of?

Interphase - cell growth and DNA replication


Mitosis - cell division

What period is divided into 3? What are they called?

Interphase


G1, synthesis and G2.

Why is mitosis needed?

Cell growth and to replace to replace damaged tissues.

Interphase (4)

- The cell prepares to divide


- DNA unravels and replicates


- Organelles replicate


- ATP content increases

Propase (4)

- The chromosomes condense, getting shorter and fatter.


- The centrioles move to opposite poles of the cell, forming protein fibres across called spindle fibres.


- The nuclear envelope break down.


- Chromosomes lie free in the cytoplasm.

Metaphase (2)

- The chromosomes (each with two chromatids) line up along the cells equator.


- The become attached to the spindle by their centromere.

Anaphase (2)

- The centromeres divide, separating each pair of sister chromatids.


- The spindles contract, pulling the chromatids to opposite ends of the cell, centromere first.

Telophase (3)

- The chromatids reach opposite poles on the spindle.


- They uncoil and become long, thin chromosomes.


- A nuclear envelope forms around each group of the chromosomes making 2 nuclei.

Cytokinesis

- The cytoplasm divides and there are two daughter cells that are genetically identical to the parent cell.

Name all the separate stages of mitosis (5)

Prophase, Metaphase, Anaphase, Telophase, Cytokinesis