Variation and Sexual Reproduction Flashcards

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1
Q

Costs of sexual reproduction?

A

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

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2
Q

Benefits of sexual reproduction?

A

increase in genetic variation in the population

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3
Q

Why can asexual reproduction be a successful reproductive strategy?

A

whole genomes are passed on from parent to offspring

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4
Q

When is maintaining the genome of the parent an advantage?

A

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

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5
Q

Examples of asexual reproduction in eukaryotes

A

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

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6
Q

Advantage of asexual reproduction?

A

offspring can be produced more often and in larger numbers

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7
Q

Parthenogenesis is more common in

A

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

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8
Q

What is parthenogenesis?

A

reproduction from a female gamete without fertilisation

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9
Q

What is meiosis?

A

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

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10
Q

In diploid cells, chromosomes typically appear as

A

homologous pairs

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11
Q

What are homologous chromosomes?

A

Same size, same centromere position, same sequence of genes at same loci

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12
Q

What are linked genes

A

those on the same chromosome

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13
Q

What can crossing over result in?

A

new combinations of the alleles of these genes

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14
Q

How many haploid cells are produced during meiosis?

A

4

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15
Q

What is the independent assortment?

A

Each pair of homologous chromosomes is positioned independently of the other pairs, irrespective of their maternal and paternal origin

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16
Q

What gene in most mammals determines the development of male characteristics?

A

The SRY gene on the Y chromosome

17
Q

What happens In homogametic females?

A

one of the two X chromosomes present in each cell is randomly inactivated at an early stage of development

18
Q

What does X chromosome inactivation prevent?

A

a double dose of gene products, which could be harmful to cells

19
Q

What are hermaphrodites?

A

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

20
Q

Other features of hermaphrodites?

A

They produce both male and female gametes and usually have a partner with which to exchange gametes

21
Q

Benefit of being a hermaphrodite?

A

If the chance of encountering a partner is an uncommon event, there is no requirement for that partner to be of the opposite sex

22
Q

In some species sex can change as a result of…?

A

size, competition, parasitic infection

23
Q

How is environmental sex determination controlled in reptiles?

A

temperature of egg incubation

24
Q

What is X chromosome inactivation?

A

A process by which most of one X chromosome is inactivated