Edexcel biology (A-level) topic 4

Niche

Full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions

Behavioural adaptations

an inherited characteristic behaviour that helps an organism survive in its environment

physiological adaptation

a physical or chemical event that occurs within the body of an organism and enables survival

Anatomical adaptations

Structural features of an organism's body that increase its chance of survival.

Evolution

Biodiversity

the variety of living organisms in the world or in a particular habitat or ecosystem

species diversity

Number of different species in an area and the abundance of each species in an area

genetic diversity

The variety of alleles within a species gene pool

Endemism

A species is unique to a singe area, geographically discrete, for example a land of vegetation

species richness

the number of different species in a community

Measure phenotype

Look at the characteristics of an organism

Measure genotype

Sample of organisms DNA

Taxonomy

The scientific study of how living things are classified. It involves naming and classifying organisms into groups based on similarities an differences.

taxonomic groups

Kingdom, Phylum, Class, Order, Family, Genus, Species

Species

A group of similar organisms that can breed and produce fertile offspring.

Seedbanks

storage centres used to preserve the biodiversity of crop and other plants. It involves keeping the seeds in dry cool conditions to inhibit germination

Seedbank pros

-cheap to store seeds rather than fully grown plants

-large no. Stored in small place

-less labour required to take care of seeds

-stored anywhere dry and cool

-seeds less likely to be damaged by disease

Seedbank cons

-testing the seeds is expensive and time consuming

-difficult to collect every seed as some plants grow remotely

breeding programme

Endangered species are bred in a controlled environment e.g zoo

Cons of breeding programmes

-animals have problems breeding outside natural habitat and die

-animal may not behave normally as bred in captivity

William Withering

English botanist, discovered digitalis (in foxgloves which treats dropsy

Drug Testing

1. Test drug on cells, small animals and larger animals

2. Test on small number of healthy pts (50)

3. Test on small number of patients (100-500)

4. Test on larger number of diseased and ensure there are no long term effects

Placebo

an inactive substance or fake treatment used as a control in an experiment- a 'dummy' drug

double-blind procedure

an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.

Antibacterial practical

1. Take extracts from mint and garlic and grind up using pestal and mortar and soak in ethanol

2. Put filter discs in solutions and carefully use sterile forceps to place on the agar jelly

3. Then do this with just ethanol

4. Incubate the plates allowing the bacteria to grow

5. Measure inhibition zone

specie evenness

Use specie richness and take into account the population size of each species

Dominant organism

a very common species in a habitat

cell wall description

-rigid structure

-surrounds plant cells

-made of cellulose

cell wall function

provides support and protection

Middle lamella description

outermost layer of the cell

Middle lamella function

-acts as adhesive

-sticks plant cells together

Plasmodesmata description

Channels in the cell walls that link adjacent cells together

Plasmodesmata function

Allow transport of substances and communication between cells

Pits description

-Regions of cell wall where wall is thin

- Arranged in pairs

Pits function

Allows transport of substances between cells

Chloroplast description

-small, flattened structure

-double bound membrane

-there are stacks called grana

Chloroplast function

Site of photosynthesis; some part in the grana some in the stomata

Amyloplast description

A small organelle enclosed by a membrane. They contain starch granules.

Amyloplast function

-starch storage

-convert starch to glucose

Vacuole and tonoplast description

The vacuole is a compartment surrounded by a membrane called tonoplast

Vacuole and tonoplast function

-vacuole contains cell sap, made of water, enzymes minerals and waste products

-vacuoles keep cells turgid and stop plant wilting

-breakdown and isolate unwanted chemicals

Xylem vessels

•Transport water and minerals up plant and provide support

•long, tube structures

•formed from dead cells joined end to end

•found together in bundles

•hollow lumen and no end walls

•water and mineral ions move in and out via pits where theres no lignin

sclerenchyma fibers

•provide support

•made of bundles of dead cells and run vertically up cell

•hollow lumen and no end walls

•cell walls thinned with lignin and have more cellulose than other plants

•particularly around outer edges of stems

How is water transported in the plant?

1. Water vapour diffuses out of stoma down diffusion gradient

2. Water evaporates out of surface of cell, lining substomatal cavity

3. Water replaced by capillary action in cell wall

4. Water drawn out of xylem

5. Continuous column of water drawn up through xylem

Starch

•main energy store in plants

•mixture of 2 polysaccharides: amylose (unbranched) and amylopectin (branched chain of glucose)

•alpha-glucose

Cellulose

•long- unbranched chains of beta-glucose joined by glycosidic bonds

•glycosidic bonds are straight so cellulose molecules straight

•

Plant fibres

•long tubes of plant cells and are strong which makes them good for rope

•this is because of the arrangement of cellulose microfibrils in cell wall & secondary thickening of the cell

Measuring tensile strength practical

1. Attach fibre to clamp stand and hang weight from middle

2. Add more weights until the fibre breaks

3. Record the mass needed to break it

4. Repeat to add reliability

5. Fibres should be the same length and variables kept consistent

Sustainability: plant fibres

• Used to make rope and fabrics

• Renewable as planted and re-grown

• Biodegradable

• Easy to grow and produce

Sustainability: starch

• Found in all plants

• Can be made into plastics

• Can produce vehicle fuel

Water

-Needed for photosynthesis

- Maintain structural rigidity

-Transport minerals and regulate temperature

Magnesium ions

-Needed for production of chlorophyll and turn plant yellow without

Nitrate ions

-Needed for production of DNA, proteins and chlorophyll

-required for plant growth, seed production and fruit production

Calcium ions

-important for plant cell wall

Investigate plant mineral deficiency

1. Take 30 seedlings of same plant and plant in separate pots

2. Make up 3 nutrient solutions made of all essential minerals but different concentrations of calcium ions

3. Split plants into 3 groups; each one only give one solution

4. Record the height of the plants after 7 weeks