Sex And Behaviour

Question 1

Which gamete is produced in larger numbers?

Answer 1

Sperm

Question 2

Which gamete has the larger energy store?

Answer 2

Egg

Question 3

What do females make a large investment in?

Answer 3

Egg structure in non-mammals or in the uterus and during gestation in mammals.

Question 4

State an advantage and disadvantage of parental investment.

Answer 4

Adv = increases the probability of production and survival of young
Disadv = costly

Question 5

Explain the differences between r-selected and k-selected.

Answer 5

• the environmental conditions in r-selected are unstable whereas k-selected are stable
• body size is smaller in r-selected while k-selected are larger
• generation time is short in r-selected and long in k-selected
• the breeding occasions in r-selected are only a few with sometimes only one while k-selected have many more
• the number of offspring produced in one cycle in r-selected is many and k-selected have a lot fewer
• parental care is limited in r-selected compared to extensive in k-selected
• offspring survival is very low in r-selected whereas it is higher in k-selected

Question 6

Explain the advantages and disadvantages of external fertilisation.

Answer 6

Adv;
- allows very large numbers of offspring to be produced

Disadv;

• many gametes are predated or not fertilised
• no or limited parental care (therefore few offspring survive)

Question 7

Explain the advantages and disadvantages of internal fertilisation.

Answer 7

Adv;

• increases chance of successful fertilisation
• fewer eggs are needed
• offspring can be retained internally for protection and for development
• higher offspring survival rate

Disadv;

• energy is used in locating a mate
• requires the difficult direct transfer of gametes from one partner to another ( therefore required complex reproductive organs and systems)

Question 8

What are mating systems?

Answer 8

Mating systems are based on how many mates an individual has during one breeding season.

Question 9

Explain what is meant by polygamy.

Answer 9

Polygamy is when individuals of one sex have more than one mate.

Question 10

Explain what is meant by monogamy.

Answer 10

Monogamy is where individuals have only one mate.

Question 11

State the term used to describe when one male mates exclusively with a group of females.

Answer 11

Polygyny

Question 12

State the term used to describe when one female mates with a number of males.

Answer 12

Polyandry

Question 13

What is meant by polygyny?

Answer 13

When one male mates exclusively with a group of females.

Question 14

What is meant by polyandry?

Answer 14

When one female mates with a number of males.

Question 15

Explain what is meant by sign stimuli.

Answer 15

Sign stimuli are actions or appearances given by individuals of a species that signal intent, often for courtship and mating.

Question 16

What is meant by fixed action patterns?

Answer 16

Fixed action patterns are instinctive sequences of behaviours which as as stimuli for responses, which in turn can act as further stimuli.

Question 17

State the term that is used when describing a female that is more inconspicuous than the male.

Answer 17

Sexual dimorphism.

Question 18

Give an example of reversed sexual dimorphism. (Not the species)

Answer 18

When females are more conspicuous than males.

Question 19

What are honest signals?

Answer 19

Honest signals can indicate favourable alleles that increase the chances of survival of offspring (fitness) or a low parasite burden, suggesting a healthy individual.

Question 20

What do lekking species do?

Answer 20

The males gather at a lek, where female choice occurs.