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Women Evolution Biology > Bio Exam 1 > Flashcards

Bio Exam 1 Flashcards

1
Q

Why do we have sexual reproduction - instead of asexual?

A

Genetic variation, better immune systems & Create offspring

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2
Q

List the troubles with sex

A

the cost of meiosis, recombination, and mating

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3
Q

Explain cost of meiosis

A

Can only pass on half your genes to your offspring

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4
Q

Explain cost of recombination

A

Mutations can be made in sexual reproduction.

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5
Q

Explain cost of mating

A

Have to spend a lot of energy on finding another mate. When you produce asexually you don’t have to spend any energy on doing so. With mating, you are exposed to STDs and predators

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6
Q

Why do people produce sexually?

A

to get rid of harmful mutations and it allows for beneficial recombination

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7
Q

Explain the Fisher-Muller “Ratchet Hypothesis

A

When you produce asexually you can’t remove any of your mutations because you’re just mating with yourself. Think of the same photocopy repeatedly being made. Sexual reproduction brings together & purges those individuals with “bad” mutations (offspring with two copies of a deleterious mutation may not survive and reproduce)

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8
Q

Explain the Williams: “Lottery Hypothesis”

A

In unstable environments do not want multiple copies of the same ‘ticket’. When you play the lottery you don’t want to buy the same ticket because you won’t be increasing your chances at winning.

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9
Q

What is the problem with the Fisher-Muller “Ratchet Hypothesis?

A

Getting rid of mutations through sex is too slow and only impacts the species rather than the individual.

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10
Q

What is the problem with the Williams: “Lottery Hypothesis”?

A

You would predict that sexual organisms would be more common in unstable environments, but they are more common in stable environments.

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11
Q

Explain W.D Hamiltion - The Red Queen Hypothesis.

A

Sexual reproduction allows us to quickly stay ahead of parasites who produce extremely quickly.

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12
Q

What is the evidence supporting the W.D Hamiltion - The Red Queen Hypothesis?

A

Animals that have a longer generation time have more recombination. More recombination keeps the host ‘ahead’ of the parasites

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13
Q

Do mammals reproduce asexually?

A

No. Only about 100 vertebrates (fish, lizards, amphibians) produce asexually.

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14
Q

Explain the characteristics of an asexual animal.

A

They’re all females because they need eggs to reproduce, they are ‘colonizers’, some species might be short-lived, and they have found other ways to mix up their genomes.

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15
Q

What are the two animals that utilize alternatives to sexual reproduction?

A

Bdelloid Rotifers & Ambystroma salamander

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16
Q

How do the Bdelloid Rotifers reproduce?

A

They extract DNA from their food,
10% of the genome comes from 500+ species, some of these species that reproduce asexually find other ways to bring in new material. There are only 450 of these species

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17
Q

How do the Ambystroma salamander
reproduce?

A

They are Kleptogenesis. They steal sperm from other closely related species to stimulate (but not fertilize) eggs. It doesn’t combine sperm. Every 1000 years it incorporates bits of stolen DNA into her genome.

18
Q

What are gametes?

A

They are sex cells that combine together to form a new organism

19
Q

Explain the problem with tiny gametes

A

They are energetically inexpensive to produce in large numbers.

20
Q

Explain the problem with intermediate gametes

A

They are too large to produce in great quantities, but too small to support early embryogenesis without additional cytoplasm.

21
Q

Explain the problem with large gametes.

A

They are energetically expensive to produce.

22
Q

What is the argument for how sex occurred?

A

Small gametes who can move fast & others that are large and have a lot of cytoplasms to support developing zygotes & there was disruptive selection with those two. They were selected against the intermediate gamete and ended up having a tiny gamete (protosperm) and a large gamete (proto-ovum)

23
Q

Can animals have both gametes?

A

No

24
Q

What are tiny gametes?

A

They are considered sperm

25
Q

What are large gametes?

A

Ova/eggs

26
Q

What is mammalian sex differentiation for females?

A

XX

27
Q

What is mammalian sex differentiation for males?

A

XY

28
Q

What is a gonad?

A

Inside genitals so testes (when they start inside) and ovaries

29
Q

What is phenotypic genes?

A

It determines what you look like on the outside. It’s more about genitalia but can also be other sexually differentiating features

30
Q

How do birds differ from mammalian sexual differentiation?

A

Females are known as XY (or WZ) & males are known as XX. The reasoning behind this is unclear.

31
Q

How does sexual differentiation differ in turtles?

A

The temperature of the egg or sand they lay the egg in determines sex. Causes problems with global warming

32
Q

When do you start as sexually bi-potential?

A

At 10 weeks old in the womb

33
Q

Explain internal differentiation

A

Both sexes start out with both female & male ducts and one system must be eliminated.

34
Q

What starts male development?

A

They have a small Y chromosome. It has regulator or controller genes that switch on the other genes for development (SRY gene)

35
Q

What is the SRY gene?

A

This is the sex determining region of the Y chromosome. It is on the short arm of the Y chromosome. It encodes for the TDF protein.

36
Q

What is the TDF protein?

A

the testes determining factor. it triggers testes to develop and these testes secrete testosteron

37
Q

What does testosterone do in internal male differentiation?

A

it promotes the differentiation of Wolffian ducts into sperm ducts (epididymis & vas deferens) and seminal vesicles

38
Q

What destroys the female - Mullerian duct?

A

The Anti-Mullerian Hormone (AMH)

39
Q

Where is AMH produced?

A

in the testes by males

40
Q

Explain the development of external male genitalia

A

The testosterone converts to DHT (dihydrotestosterone). If the androgens are present, the testes then will drop into the scortum

41
Q

Are testes still inside the body while in development?

A

True

42
Q
A

Women Evolution Biology (1 decks)

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