Sex and gender differences 1

Question 1

Define sex
Specific a____ that characterise m____ or f____
Includes c____ and other g____ attributes, as well as p____, p____ and b____ differences

Answer 1

Specific attributes that characterise maleness or femaleness. They can include chromosomal and other genetic attributes, as well as physiological, physical and behavioural differences.

Question 2

Define gender

Answer 2

A person’s internal sense of their gender (experienced gender) or the way in which their gender is perceived by others (expressed gender).

Question 3

What are Tinbergen (1963) “Four questions”?

Answer 3

1. How did the behaviour evolve?
2. How does it enhance biological fitness?
3. How does it develop in an individual or social group?
4. What are the physiological and brain mechanisms involved?

Question 4

Define haploid and diploid

Answer 4

Haploid - having a single copy of each chromosome in a cell
Diploid - having two copies of each chromosome in a cell

Question 5

Finish the sentences about sexual reproduction…
1. More complex type of cell division followed by …………
2. Deleterious mutations may accumulate, masked by ……….
3. Risks of finding/competing for ……

Answer 5

1. fertilisation
2. a normal second copy of a gene
3. mates

Question 6

Compare mitosis and meiosis

Answer 6

In mitosis in a diploid cell (left) the chromosomes replicate and then separate into the daughter cells. In meiosis (right) chromosome duplication is followed by recombination and generation of haploid gametes – Fusion of two gametes in sexual reproduction restores the diploid state.

Question 7

Fill in the gaps about an evolutionary perspective on sex:
1. Sun and planets condensed out of a spinning gaseous cloud about _____ years ago
2. Earth and a large ______ collided about ____ years ago, resulting in the formation of the ___ and possibly also the large _____ content on Earth
3. Life also evolved some ____ years ago
4. Sexual reproduction evolved in ________ at least _____ years ago
4. Sexual reproduction remains ______, even in those groups where ___________ is also present (e.g. ants, bees, wasps, water fleas)

Answer 7

1. 5 billion
2. asteroid, 4.5 billion, moon, water
3. 4.5 billion
4. predominant, parthenogenesis

Question 8

What are four hypotheses of why sexual reproduction has persisted?

Answer 8

1. Recombination of different genotypes during meiosis allows favourable mutations to come together in the same individual.
2. Recombination allows more rapid adaptation to fluctuating environments (e.g. to new parasites - the Red Queen hypothesis).
3. May help to avoid accumulation of deleterious mutations, especially in stressful environments.
4. Parthenogenesis (as in bees, ants & wasps and many other invertebrates) permits rapid exploitation of a favourable environment. Switch back to sex as things become more stressful, favourable season ends etc. Very rare in vertebrates.

Question 9

The magnitude of a difference between two groups can be expressed as what?

Answer 9

The effect size
(Cohen’s d – the difference in the means divided by the relevant standard deviation)

Question 10

Sexual dimorphism tends to be high and low in what conditions?

Answer 10

High in primates with significant male-male competition
Low in those that either breed cooperatively or are relatively solitary

Question 11

Meiosis leads to _______ of gene variants between homologous chromosomes

Answer 11

Recombination

Question 12

XX mouse embryos with male phenotype can be shown to have incorporated what gene into one of their X chromosomes?

Answer 12

Sry

Question 13

The human SRY gene can produce what when incorporated into a developing mouse foetus?

Answer 13

masculinisation

Question 14

In some rare instances, individuals with an XY genotype and female phenotype. These may be accounted for by mutations in the what?

Answer 14

sex steroid signalling pathways

Question 15

What are hormones?
C____ messangers produced in one part of the b____, typically then r____ into the b____ and act at r____ on cells of another o____ or t____

Answer 15

Chemical messengers produced in one part of the body, typically then released into the blood and act at receptors on cells of another organ or tissue.

Question 16

What is special about steroid hormones?

Answer 16

Although most hormones bind to receptors on a cell surface, steroid hormones are fat soluble and can pass directly through the external cell membrane and bind to receptors. The hormone-receptor complex may then pass into the cell nucleus and directly affect gene transcription
steroids may also bind to different receptors at the cell surface, perhaps modifying the effects of a brain neurotransmitter and producing rapid effects on behaviour

Question 17

Where do the following hormones come from and what do they do?
1. Androgens, oestrogens and progestins
2. Luteinising hormones and follicle stimulating hormones
3. Gonadotrophin releasing hormone

Answer 17

1. are steroid hormones mostly secreted, respectively, by the testes and ovaries.
2. large protein hormones secreted by the pituitary gland (both sexes) and known as ‘gonadotrophins’ because they stimulate hormone release from the testes and ovaries (gonads).
3. smaller peptide secreted by the hypothalamus that stimulates the release of gonadotrophins.
   (The steroid hormones inhibit the production of GnRH, LH and FSH – negative feedback control. )

Question 18

A drug that blocks GnRH receptors will stop what?

Answer 18

The secretion of FSH and LH from the pituitary, and also the production of hormones by the gonads