3a: Cost and Benefits of Sexual and Asexual Reproduction

Question 1

Costs of sexual reproduction

Answer 1

• males unable to produce offspring
• only half of each parent’s genome passed onto offspring, disrupting successful parental genomes

Question 2

Why do benefits of sexual reproduction outweigh costs

Answer 2

due to an increase in genetic variation in the population

Question 3

Genetic variation provides…

Answer 3

the raw material required for adaptation, giving sexually reproducing organisms a better chance of survival under changing selection pressures

Question 4

Why does co-evolutionary interactions between parasites and hosts may select for sexually reproducing hosts

Answer 4

• Hosts better able to resist and tolerate parasitism have greater fitness.
• Parasites better able to feed, reproduce and find new hosts have greater
  fitness.

Question 5

If hosts reproduce sexually, the genetic variability in their offspring reduces the chances that…

Answer 5

all will be susceptible to infection by parasites

Question 6

Asexual reproduction can be a successful reproductive strategy as…

Answer 6

• whole genomes are passed on from parent to offspring
• Offspring can be reproduced more often and in larger numbers with asexual
  reproduction

Question 7

Maintaining the genome of the parent is an advantage particularly in… (asexual reproduction)

Answer 7

very narrow, stable niches or when re-colonising disturbed habitats

Question 8

examples of asexual reproduction

Answer 8

-vegetative cloning in plants
- parthenogenesis in lower plants and animals that lack fertilisation

Question 9

What is parthenogenesis

Answer 9

reproduction from a female gamete without fertilisation.

Question 10

Parthenogenesis is more common in…

Answer 10

• cooler climates, which are disadvantageous to parasites,
• regions of low parasite density or diversity

Question 11

Asexually reproducing populations are not able to adapt easily to changes in their environment, but…

Answer 11

mutations can occur that provide some degree of variation and enable some natural selection and evolution to occur

Question 12

Organisms that reproduce principally by asexual reproduction also often have ________ to increase variation

Answer 12

mechanisms for horizontal gene transfer between individuals to increase variation

Question 13

Meiosis definition

Answer 13

is the division of the nucleus that results in the formation of haploid gametes
from a diploid gametocyte