Unit 4

Question 1

What two processes must sexual reproduction include?

Answer 1

Meiosis and fusion of gametes.

Question 2

Define fertilization.

Answer 2

Fusion of male and female gametes.

Question 3

What does meiosis create?

Answer 3

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

Question 4

What is a diploid?

Answer 4

A cell with two copies of most genes.

Question 5

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

Answer 5

The gametes that fuse are nearly identical.

Question 6

Define anisogamous.

Answer 6

Different male and female gametes.

Question 7

Which organisms are anisogamous?

Answer 7

All plants and animals.

Question 8

What regulates the menstrual cycle?

Answer 8

Uterine and ovarian cycles.

Question 9

When does the menstrual cycle begin and end?

Answer 9

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

Question 10

What happens in the follicular phase of the ovarian cycle?

Answer 10

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

Question 11

What happens in the luteal phase of the ovarian cycle?

Answer 11

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.

Question 12

What happens during the luteal phase of the uterine cycle?

Answer 12

The endometrium becomes thicker in preparation for embryo implantation

Question 13

What happens if no implantation occurs in the uterine cycle?

Answer 13

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

Question 14

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

Answer 14

Usually lasts 4-7 days.

Question 15

Which hormones are produced by the pituitary gland?

Answer 15

FSH, LH, ADH, oxytocin, prolactin

Question 16

Which hormones are produced by the ovaries?

Answer 16

Oestradiol and progesterone.

Question 17

Role of FSH?

Answer 17

Stimulates release of oestradiol and development of follicles.

Question 18

Role of Oestradiol?

Answer 18

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

Question 19

Role of LH?

Answer 19

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

Question 20

Role of Progesterone?

Answer 20

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

Question 21

What forms a zygote?

Answer 21

Sperm and egg combining.

Question 22

How do sperm find the egg?

Answer 22

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

Question 23

What is the zona pellucida?

Answer 23

Protective glycoproteins around the egg.

Question 24

What happens immediately after fertilization?

Answer 24

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

Question 25

Define gametogenesis.

Answer 25

The production of gametes.

Question 26

What are the male and female gametes called?

Answer 26

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

Question 27

Steps of gametogenesis?

Answer 27

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

Question 28

Where does spermatogenesis occur?

Answer 28

In the testicles.

Question 29

What is the role of Leydig cells?

Answer 29

Fill gaps between seminiferous tubules.

Question 30

What do Sertoli cells do?

Answer 30

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

Question 31

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

Answer 31

Generation of cells that undergo meiosis and differentiate into sperm.

Question 32

When is the first stage of oogenesis completed?

Answer 32

Prior to birth.

Question 33

What happens to primary follicles at birth?

Answer 33

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

Question 34

What stimulates primary follicles to develop during each menstrual cycle?

Answer 34

FSH

Question 35

Define polyspermy

Answer 35

Fusion of more than one sperm with an egg

Question 36

What reactions prevent polyspermy?

Answer 36

Acrosome reaction and cortical reaction.

Question 37

What is down-regulation in IVF?

Answer 37

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

Question 38

What happens during follicle-stimulation in IVF?

Answer 38

Injections of FSH and LH stimulate follicle development.

Question 39

What is mixed with each egg during IVF?

Answer 39

50,000 to 100,000 sperm.

Question 40

How is the uterus prepared for implantation in IVF?

Answer 40

Extra progesterone is given to ensure the uterus lining is maintained

Question 41

Define homeostasis.

Answer 41

Maintaining stable internal conditions

Question 42

What feedback mechanisms are used in homeostasis?

Answer 42

Positive and negative feedback.

Question 43

Example of positive feedback in the body?

Answer 43

Increasing muscle contractions during childbirth.

Question 44

What do alpha cells in the pancreas secrete?

Answer 44

Glucagon

Question 45

What do beta cells in the pancreas secrete?

Answer 45

Insulin

Question 46

Role of glucagon?

Answer 46

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

Question 47

Role of insulin?

Answer 47

Stimulates uptake of glucose, lowering blood glucose levels.

Question 48

Define thermoregulation.

Answer 48

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

Question 49

What is the normal core body temperature for humans?

Answer 49

37 degrees Celsius.

Question 50

How does vasoconstriction affect body temperature?

Answer 50

Reduces heat loss by constricting arterioles to the skin.

Question 51

How does vasodilation affect body temperature?

Answer 51

Increases heat loss by expanding arterioles to the skin.

Question 52

Define osmoregulation.

Answer 52

Regulation of osmotic levels within narrow set limits.

Question 53

What is the basic functional unit of the kidney?

Answer 53

The nephron.

Question 54

What does the Bowman's capsule do?

Answer 54

Collects fluid filtered from blood.

Question 55

Role of the glomerulus?

Answer 55

High-pressure capillary bed where blood filtration occurs.

Question 56

What is the loop of Henle's function?

Answer 56

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

Question 57

What is ultrafiltration?

Answer 57

Filtering of blood to form urine.

Question 58

What is HRT used for?

Answer 58

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

Question 59

Potential risks of HRT?

Answer 59

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

Question 60

Symptoms of menopause?

Answer 60

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