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Zoology 1 > Reproduction 1 > Flashcards

Reproduction 1 Flashcards

1
Q

Define reproduction

A

production of offspring

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2
Q

Describe 3 key features of asexual reproduction

A
  1. All offspring are genetically identical (clones)
  2. Copying and proliferation in both unicellular + multicellular
  3. Transmission of an intact, single parental genome but mutations also transferred
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3
Q

Is asexual reproduction widespread across the animal kingdom? Give some examples

A

Yes it is. e.g komodo dragons, sponges, bees/wasps etc.
Some organisms can reproduce both sexually (when conditions are favourable) & asexually (when they are unfavourable) e.g Daphnia

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4
Q

List the 4 types of asexual reproduction

A
  1. Fragmentation/regeneration
  2. Binary fission
  3. Budding
  4. Parthenogenesis
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5
Q

Define fragmentation/regeneration as a type of asexual reproduction

A

parent broken into pieces = adults, followed by regeneration e.g starfish

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6
Q

Define budding

A

Offspring grows out of the parent. Specialised masses of cells are released from the parent that can develop into offspring e.g Hydra

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7
Q

Define Parthenogenesis

A

Virgin birth. Unfertilised eggs develop into offspring but are not haploid. Occurs in several fish, insects, reptiles but NOT mammals due to genomic imprinting

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8
Q

In a low stress environ, will an animal reproduce asexually or sexually?

A

Asexually

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9
Q

In a high stress environ, will an animal reproduce asexually or sexually?

A

Sexually

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10
Q

Why do organisms produce sexually in high stress environments (as opposed to asexually)

A

Because it promotes genetic variation in offspring if environ is unfavourable (stressful)

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11
Q

What is the main con of asexual reproduction?

A

Parental mutations are passed to offspring –> no genetic variation

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12
Q

What are the 3 stages of sexual reproduction?

A
  1. Gametogenesis
  2. Mating
  3. Fertilisation
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13
Q

Define gametogenesis

A

production of gametes
- evolutionarily conserved

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14
Q

Define mating

A

transferring of gametes
- extraordinarily diverse

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15
Q

Define fertilisation

A

fusion of gametes
- evolutionarily conserved

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16
Q

What are the 2 stages of gametogenesis?

A
  1. Meiosis (diploid cell → haploid cell)
  2. Spermatogenesis and oogenesis
17
Q

Describe spermatogenesis

A
  • Produced from spermatogonial stem cells → divide by mitosis initially = diploid primary spermatocytes
  • 1 primary spermatocyte = 4 sperm cells
18
Q

Describe spermatogenesis in mammals

A
  • Occurs in seminiferous tubules within testes
  • From periphery to lumen
  • Starts in puberty
  • Sperm produced in approx. 74 days
  • Stored in epididymis for <4 weeks or reabsorbed
  • Semen from seminal vesicles & prostate gland
19
Q

Describe spermatogenesis in insects

A
  • Occurs in cysts within testes
  • From distal to proximal (outside to centre)
  • Starts in larval stage
  • Sperm produced in a few days
  • Stored in seminal vesicle
  • Semen from accessory gland
20
Q

Gametogenesis: at puberty the hypothalamus secretes what?

A

GnRH

21
Q

What does GnRH do?

A

Stimulates FSH and LH from anterior pituitary cells

22
Q

What does FSH stand for?

A

Follicle stimulating hormone

23
Q

What does FSH do in ‘males’?

A

stimulates development of seminiferous tubes (where sperm form) & spermatogenesis acting together with testosterone by stimulating Sertoli cells

24
Q

What does LH stand for?

A

luteinizing hormone

25
Q

What does LH do in males?

A

stimulates Leydig cells to secrete testosterone which stimulates spermatogenesis

26
Q

Describe sperm morphology

A
  • Head (nucleus)
  • Neck (sperm centriole for tail formation and movement, and embryo development)
  • Midpiece (mitochondria → ATP for energy)
  • Tail (propels sperm forwards)
27
Q

Give an example of sperm gigantism

A

fruit fly body length = 3mm/ sperm length = 60mm

Zoology 1 (26 decks)

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