2.3 Variation And Sexual Reproduction

Question 1

Asexual Reproduction Costs

Answer 1

• lack of genetic variation
• harmful alleles last longer in gene pool
• not able to adapt easily to environmental conditions

Question 2

Asexual Reproduction Benefits

Answer 2

• lower metabolic costs
• rapid offspring production
• every member can reproduce
• whole genome passed on

Question 3

Sexual reproduction Costs

Answer 3

• higher metabolic costs (production of gamete’s)
• only half population can reproduce
• slow offspring production
• only half genome passed on

Question 4

Benefits of Sexual Reproduction

Answer 4

• increased genetic variation
• continual adaptation possible

Question 5

Why is sexual reproduction more common than asexual

Answer 5

Because benefits of sexual reproduction must outweigh the benefits. Meaning genetic variation allows adaptation which increases chances of survival.

Question 6

What relation does genetic variation have to red queen hypothesis

Answer 6

Red queen would stop as no species would adapt and pressure other species

Question 7

what type of reproduction has an advantage against parasitism?

Answer 7

sexual reproduction

Question 8

what is the relation between parasitism and the fitness of the host

Answer 8

The fitter the host the better they are able to resist parasitism

Question 9

why is sexual reproduction at an advantage with parasitism

Answer 9

If hosts reproduce sexually, the genetic variability in their offspring reduces the chances
that all will be susceptible to infection by parasites

Question 10

When is passing on the whole genome advantageous

Answer 10

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

Question 11

Examples of asexual reproduction in eukaryotes are

Answer 11

parthenogenesis and vegetative cloning in plants

Question 12

What is parthenogenesis

Answer 12

the asexual production of offspring without males or fertilisation. Occurs due to female gamete alone

Question 13

What conditions is parthenogenesis most common in

Answer 13

cooler climates and lower parasite density

Question 14

What way, other than random mutations, can asexual reproduction experience genetic variation

Answer 14

Horizontal gene transfer

Question 15

What is the result of horizontal gene transfer compared to vertical gene transfer

Answer 15

horizontal gene transfer results in faster evolutionary
change than in organisms that only use
vertical transfer.

Question 16

What is a homologus chromosome

Answer 16

Homologous chromosomes are
chromosomes of the same size, same
centromere position and with the same
sequence of genes at the same loci.

Question 17

Meiosis process on flashcard

Answer 17

:)

Question 18

Define hermaphrodites

Answer 18

Species that have functioning male and female reproductive organs in each individual

Meaning on individual can produce both male and female gametes

Question 19

What is the benefit of hermaphroditism

Answer 19

If the chances of encountering a partner/mate is uncommon, there is no requirement of the partner to be of the opposite gender

Question 20

Describe environmental sex determination in crocodiles

Answer 20

Sex determination is controlled by temperature at which eggs are incubated

Question 21

Sex ratio of offspring can be adjusts by

Answer 21

Population density and the resulting strain on resource availability

Question 22

Sex can change in some species as a result of

Answer 22

• Size
• Parasitic infection
• Competition

Question 23

In most mammals which gene determines the development of male characteristics

Answer 23

SRY Gene on the Y chromosome

Question 24

What do homogametic males lack on the shorter chromosome? and what is the result of that?

Answer 24

Most of the corresponding homologus alelles

This can result in sex-linked patterns of inheritance

Question 25

What is X chromosome inactivation

Answer 25

a process by which most of one X chromosome is inactivated.

Question 26

What happens in homogametic females at a young age

Answer 26

In homogametic females (XX) one of the two X chromosomes present in each cell is randomly inactivated at an early stage of development

Question 27

What does X Chromosome inactivation prevent? and how dos this affect carriers of sex linked diseases

Answer 27

A double does of gene products, which could be harmful to cells

Carriers are less likely to be affected by any deleterious mutations on these X chromosomes

Question 28

Why is it significant that a random x chromosome is inactivated in females?

Answer 28

Half of the cells in any tissue will have a working copy of the gene in question