Biodiversity and endemism

Question 1

How is the heterozygosity index measured (genetic diversity)?

Answer 1

H = no. of heterozygotes / no. of total indivs in the pop.

Question 2

What is the formula for SDI (species diversity)?

Answer 2

D = N(N-1) / ∑n (n-1)

Question 3

What are the three types of adaptations?

Answer 3

Behavioural - courtship rituals e.g scorpions ‘dance’
Anatomical - whales have thick fat layers for insulation
Physiological - brown bears hibernate to lower their BMR and energy consumption

Question 4

What is the formula for the first Hardy-Weinberg equation?

Answer 4

p (freq. of dominant allele) + q (freq. of recessive allele)
= 1

Question 5

What is the formula for the second Hardy-Weinberg equation?

Answer 5

p2 (freq. of homo dom.) + 2pq (freq. of hetero.) + q2 (freq. of homo reces.) = 1

Question 6

What assumptions is the HW equation based on?

Answer 6

• Large population
• No immigration or emigration
• No mutations or natural selection
• Random mating

Question 7

What are plasmodesmata and what’s their function?

Answer 7

Channels in the cell walls of plant cells - allow transport and communication between adjacent cells.

Question 8

What is the middle lamella and what’s its function?

Answer 8

Outermost layer of a plant cell - acts as an adhesive, sticks adjacent cells together and thus provides stability.

Question 9

What are pits and what’s thier function?

Answer 9

Pits are very thin sections of the cell wall which allow for substance transport.

Question 10

What are amyloplasts and what’s their function?

Answer 10

Amyloplasts are membrane-bound and store starch granules.

Question 11

What is the vacuole and tonoplast, what are their functions?

Answer 11

Vacuole contains cell sap which includes minerals and enzymes. It also keeps the cell turgid, prevents wilting.
Tonoplast - membrane of the vacuole.

Question 12

What are the properties and functions of xylem vessels?

Answer 12

Long, tube-like structures consisting of dead cells with no end walls. Their lumen is hollow. Cell walls are strengthened by lignin.
The function of xylem is to provide support and to transport water and mineral ions - pits in the cell wall allow exchange.

Question 13

What are the properties and functions of schlerenchyma fibres?

Answer 13

Sclerenchyma are made of dead cells with a hollow lumen, but these have end walls. The cell walls contain extra cellulose and lignin.
Their function is to provide support.

Question 14

What are the properties and functions of phloem tissue?

Answer 14

Phloem contain sieve tube elements which join end to end to form sieve tubes. Sieve tube elements have perforated end walls to allow solutes to pass. Sieve tube elements have a lack of a nucleus and other organelles - companion cells carry out their living functions and their own.
Phloem tissue’s function is to transport organic solute like sucrose.

Question 15

What are the properties of cellulose?

Answer 15

Long, unbranched chains of beta glucose, joined by 1-4 glycosidic bonds which are straight. Between 50-80 cellulose chains are linked by many H bonds - forming strong microfibrils.

Question 16

What are the phases of a clinical trial?

Answer 16

1. New drugs tested on a small group of healthy people to figure out dosage, sdie effects and the body’s reaction.
2. Drug is tested on a larger group of patients to test how well it works.
3. Drug is compared to existing treatments and sample size increases massively.

Question 17

In which phase are patients typically given placebos and why?

Answer 17

Phase 2: half the patients are given a placebo, the other half are given the real drug. This is to figure out whether the drug actually has an effect i.e. the effect of the real drug is greater than the ‘placebo effect’.

Question 18

What are the advantages of a double blind study design?

Answer 18

Reduces bias in results as the effect of the investigator’s and patient’s attitudes on the results are negated. For example, if a doctor knows someone has received the real drug, they may think they’ve improved more than they actually have.