2.3.1 variation and sexual reproduction

Question 1

what are the costs of sexual reproduction

Answer 1

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

Question 2

how do benefits outweigh the costs of sexual reproduction

Answer 2

due to the increase in genetic variation in the population

Question 3

what does genetic variation provide

Answer 3

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

Question 4

what does the red queen hypothesis explain

Answer 4

the persistence of sexual reproduction

Question 5

what does the red queen hypothesis explain about the persistence of sexual reproduction

Answer 5

co-evolutionary interactions between parasites and hosts may select for sexually reproducing hosts.
hosts better able to resist and tolerate parasitism have greater fitness. parasites are better able to feed, reproduce and find new hosts with greater fitness.

Question 6

what happens if hosts reproduce sexually

Answer 6

the genetic variability in their offspring reduces the chances that all will be susceptible to infection by parasites

Question 7

why can asexual reproduction be successful as a reproductive strategy

Answer 7

whole genomes are passed on from parent to offspring

Question 8

what happens in asexual reproduction

Answer 8

just one parent can produce daughter cells and established a colony of virtually unlimited size over time

Question 9

when is maintaining the genome of the parent an advantage

Answer 9

in narrow, stable niches or when recolonising disturbed habitats

Question 10

what is an example of asexual reproduction in eukaryotes

Answer 10

vegetative cloning in plants and parthogenesis in lower plants and animals that lack fertilisation

Question 11

what is parthogenesis

Answer 11

reproduction from a female gamete without fertilisation

Question 12

is offspring reproduced more often and in larger numbers through asexual or sexual reproduction

Answer 12

asexual

Question 13

when is parthogenesis more common

Answer 13

in cooler climates

Question 14

parthogenesis is more common in cooler climates, which is disadvantageous to who?

Answer 14

parasites or regions of low parasite density or diversity

Question 15

what are the cons of asexual reproduction

Answer 15

asexually reproducing populations are not able to adapt easily to changes in their environment - mutations can occur that provide some degree of variation and enable some natural selection and evolution to occur

Question 16

what do organisms who reproduce asexually have mechanisms for?

Answer 16

horizontal gene transfer between individuals, which increases variation for example between the plasmids of bacteria and yeast

Question 17

prokaryotes can exchange genetic material horizontally. what does this result in?

Answer 17

faster evolutionary change than in organisms that only use vertical transfer