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HL Biology Year 1 > Unit 4 > Flashcards

Unit 4 Flashcards

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1
Q

What two processes must sexual reproduction include?

A

Meiosis and fusion of gametes.

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2
Q

Define fertilization.

A

Fusion of male and female gametes.

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3
Q

What does meiosis create?

A

Gamete cells, which are haploids that combine to form a diploid with distinct genetic information from both parents.

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4
Q

What is a diploid?

A

A cell with two copies of most genes.

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5
Q

What is the nature of gametes in many types of fungi?

A

The gametes that fuse are nearly identical.

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6
Q

Define anisogamous.

A

Different male and female gametes.

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7
Q

Which organisms are anisogamous?

A

All plants and animals.

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8
Q

What regulates the menstrual cycle?

A

Uterine and ovarian cycles.

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9
Q

When does the menstrual cycle begin and end?

A

Begins at puberty and ends at menopause or due to ill-health

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10
Q

What happens in the follicular phase of the ovarian cycle?

A

A group of follicles develop in the ovary; the most developed follicle breaks open around day 14 (ovulation), and other follicles degenerate.

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11
Q

What happens in the luteal phase of the ovarian cycle?

A

The wall of the follicle that released the egg develops into a corpus luteum, which breaks down if fertilization does not occur, and the cycle repeats.

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12
Q

What happens during the luteal phase of the uterine cycle?

A

The endometrium becomes thicker in preparation for embryo implantation

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13
Q

What happens if no implantation occurs in the uterine cycle?

A

The endometrium sheds during menstruation (referred to as a “period”).

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14
Q

When does the “period” set day 1 of the menstrual cycle?

A

Usually lasts 4-7 days.

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15
Q

Which hormones are produced by the pituitary gland?

A

FSH, LH, ADH, oxytocin, prolactin

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16
Q

Which hormones are produced by the ovaries?

A

Oestradiol and progesterone.

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17
Q

Role of FSH?

A

Stimulates release of oestradiol and development of follicles.

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18
Q

Role of Oestradiol?

A

Stimulates thickening of the endometrium and boosts FSH, leading to a positive feedback loop until it stimulates LH production and inhibits FSH production.

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19
Q

Role of LH?

A

Peaks at the end of the follicular phase, stimulates meiosis completion, ovulation, and development of the corpus luteum.

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20
Q

Role of Progesterone?

A

Encourages thickening and maintenance of the endometrium, inhibits FSH and LH secretion.

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21
Q

What forms a zygote?

A

Sperm and egg combining.

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22
Q

How do sperm find the egg?

A

Chemical signals released by the egg are detected by the sperm.

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23
Q

What is the zona pellucida?

A

Protective glycoproteins around the egg.

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24
Q

What happens immediately after fertilization?

A

The egg hardens the zona pellucida to ensure a diploid zygote with no more than two sets of chromosomes.

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25
Q

Define gametogenesis.

A

The production of gametes.

26
Q

What are the male and female gametes called?

A

Male: Spermatozoa (sperm), Female: Oocytes (eggs).

27
Q

Steps of gametogenesis?

A

Mitosis, cell growth, two divisions of meiosis, differentiation.

28
Q

Where does spermatogenesis occur?

A

In the testicles.

29
Q

What is the role of Leydig cells?

A

Fill gaps between seminiferous tubules.

30
Q

What do Sertoli cells do?

A

Exist in the wall of the tubule, nurturing developing sperm.

31
Q

What is the result of continuous mitosis in the germinal epithelium?

A

Generation of cells that undergo meiosis and differentiate into sperm.

32
Q

When is the first stage of oogenesis completed?

A

Prior to birth.

33
Q

What happens to primary follicles at birth?

A

Approximately 400,000 primary follicles exist, and no more are produced after birth.

34
Q

What stimulates primary follicles to develop during each menstrual cycle?

A

FSH

35
Q

Define polyspermy

A

Fusion of more than one sperm with an egg

36
Q

What reactions prevent polyspermy?

A

Acrosome reaction and cortical reaction.

37
Q

What is down-regulation in IVF?

A

Administration of FSH and LH inhibiting injections to pause the menstrual cycle.

38
Q

What happens during follicle-stimulation in IVF?

A

Injections of FSH and LH stimulate follicle development.

39
Q

What is mixed with each egg during IVF?

A

50,000 to 100,000 sperm.

40
Q

How is the uterus prepared for implantation in IVF?

A

Extra progesterone is given to ensure the uterus lining is maintained

41
Q

Define homeostasis.

A

Maintaining stable internal conditions

42
Q

What feedback mechanisms are used in homeostasis?

A

Positive and negative feedback.

43
Q

Example of positive feedback in the body?

A

Increasing muscle contractions during childbirth.

44
Q

What do alpha cells in the pancreas secrete?

A

Glucagon

45
Q

What do beta cells in the pancreas secrete?

A

Insulin

46
Q

Role of glucagon?

A

Stimulates breakdown of glycogen into glucose, increasing blood glucose levels.

47
Q

Role of insulin?

A

Stimulates uptake of glucose, lowering blood glucose levels.

48
Q

Define thermoregulation.

A

Control of core body temperature to keep it close to a set point.

49
Q

What is the normal core body temperature for humans?

A

37 degrees Celsius.

50
Q

How does vasoconstriction affect body temperature?

A

Reduces heat loss by constricting arterioles to the skin.

51
Q

How does vasodilation affect body temperature?

A

Increases heat loss by expanding arterioles to the skin.

52
Q

Define osmoregulation.

A

Regulation of osmotic levels within narrow set limits.

53
Q

What is the basic functional unit of the kidney?

A

The nephron.

54
Q

What does the Bowman’s capsule do?

A

Collects fluid filtered from blood.

55
Q

Role of the glomerulus?

A

High-pressure capillary bed where blood filtration occurs.

56
Q

What is the loop of Henle’s function?

A

Carries filtrate deep into the medulla and back to the cortex.

57
Q

What is ultrafiltration?

A

Filtering of blood to form urine.

58
Q

What is HRT used for?

A

To relieve menopausal symptoms by supplementing levels of oestrogen and progesterone.

59
Q

Potential risks of HRT?

A

ncreases the risk of coronary artery disease but decreases the chance of weak bones (osteoporosis).

60
Q

Symptoms of menopause?

A

Hot flushes, reduced sex drive, vaginal dryness, night sweats, mood swings.

HL Biology Year 1 (5 decks)

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