Genetics and Evolution

Question 0

Outline a physiological adaptation seen in desert mammals

Answer 0

The kidneys of desert mammals are adapted in such a way as to produce very concentrated urine, thereby saving water

Question 1

Describe how animals may be structurally adapted to living in cold climates

Answer 1

Penguins have a small surface area to volume ratio and are structurally adapted to living in cold environments by having a thick layer of insulating fat and waterproof insulating feathers

Question 2

Describe how cacti are adapted to living in arid environments

Answer 2

Cacti have extensive root systems to take up water, various mechanisms to reduce water loss by transpiration, as well as water storage systems to survive arid environments

Question 3

Explain what is meant by the term speciation

Answer 3

Speciation refers to the formation of a new species of organisms

Question 4

Describe the conditions essential for speciation to occur

Answer 4

Two populations of the parent species must become geographically isolated so that gene flow between them is prevented

Interbreeding between the populations to produce fertile offspring eventually becomes impossible - the two populations have become different species

Question 5

Describe what is meant by the term sympathies speciation

Answer 5

Sympatric speciation is the development of one or more species, which occurs when populations of the parent species living in the same area are prevented from interbreeding – the two populations are said to be reproductively isolated from each other

Question 6

Name the four main causes of reproductive isolation

Answer 6

Seasonal isolation

Mechanical isolation

Behavioural isolation

Gametic isolation

Question 7

A male donkey and a female horse can reproduce successfully to produce a viable offspring (a mule). However, this offspring is infertile.

What king of isolating mechanism separates donkeys and horses?

Answer 7

Post-zygotic isolating mechanism

Question 8

Name the hormone that stimulates the development of male secondary sexual characteristics

Answer 8

Testosterone

Question 9

Name the hormone that maintains the lining of the uterus

Answer 9

Progesterone

Question 10

Name the hormone that stimulates the development of female secondary sexual characteristics

Answer 10

Oestrogen

Question 11

Name the hormone that stimulates ovulation

Answer 11

Lutenising hormone (LH)

Question 12

Name the hormone that stimulates the production of gametes

Answer 12

Follicle-stimulating hormone (FSH)

Question 13

Explain why progesterone is used in oral contraceptives

Answer 13

Progesterone inhibits the production of FSH and so prevents development of an ovum

Progesterone also inhibits the production of LH and so prevents ovulation