Unit 2: KA4 - Sex and Behaviour

Question 1

Define the term: parental investment

Answer 1

Parental investment is all of the energy costs that parents incur during their reproduction strategy and care of offspring.

Question 2

Why is parental investment important?

Answer 2

It increases the probability of production and survival of young.

Question 3

Which parent invests more energy?

Answer 3

The female.

Question 4

Compare egg cells and sperm cells.

Answer 4

Egg:
- 1 at a time
- large
- large energy store
Sperm:
- 300 million at a time
- small
- no energy store

Question 5

Describe female investment in mammals and non-mammals

Answer 5

Mammals: Uterus and during gestation

Non-mammals: Investment in egg structure

Question 6

Which two factors are organisms classified as ‘r’ or ‘k’ selected based upon?

Answer 6

• level of parental investment

- number of offspring

Question 7

What are the differences between ‘r-selected’ and ‘k-selected’ organisms.

Answer 7

r-selected: small level of parental investment, large number of offspring, small size
k-selected: large level of parental investment, small number of offspring, large size

Question 8

Describe internal and external ferilisation

Answer 8

Internal: egg fertilised inside female’s body
External: egg fertilised outside of female’s body

Question 9

Describes the costs of External fertilisation

Answer 9

• Many gametes unfertilised/predated
• No or limited parental care
• Few offspring survive

Question 10

Describe the benefit of external fertilisation

Answer 10

• Very large number of offspring can be produced

Question 11

Describe the cost of internal fertilisation

Answer 11

• mate must be located, expending energy

- Gametes must be directly transferred to the other partner

Question 12

Describe the benefits of internal fertilisation

Answer 12

• Increased chance of fertilisation
• fewer eggs needed
• offspring retained internally for protection and development
• Higher offspring survival rate

Question 13

What are mating systems based on?

Answer 13

How many mates an individual has during one breeding season.

Question 14

Describe monogamy

Answer 14

The mating of a pair of animals to the exclusion of all others.

Question 15

Describe Polygamy and its two types.

Answer 15

Individuals of one sex have more than one mate
Polygyny: one male mates exclusively with a group of females
Polyandry: One female mates with a number of males in the same breeding season

Question 16

Define the term: courtship ritual

Answer 16

A specialised behaviour in animals that attracts a member of the opposite sex and leads to mating

Question 17

What two factors can successful courtship behaviour be a result of in birds and fish.

Answer 17

• species-specific sign stimuli

- fixed action pattern response

Question 18

Describe what sexual selection selects for.

Answer 18

characteristics that have little survival benefit for the individual but increases their chances of mating.

Question 19

Describe sexual dimorphism.

Answer 19

Any physical differences between males and females as a result of sexual selection.
Females becoming inconspicuous, males becoming more conspicuous

Question 20

Describe reverse sexual dimorphism

Answer 20

When the normally inconspicuous female is larger or more ornate than the male

Question 21

Describe ‘honest signals’.

Answer 21

Signals revealed by males that indicate:
- favourable alleles
- low parasite burden
Allowing the females to assess genetic quality

Question 22

Describe lekking

Answer 22

Males will gather to carry out a communal display, encouraging female choice

Question 23

Define the term ‘satellite males’

Answer 23

subordinate and juvenile males who are found at the fringes of a lek

Question 24

What does success in male-male rivalry do?

Answer 24

It increases access to females for mating.

Question 25

What will males fight for?

Answer 25

• Dominance

- Access to females

Question 26

What will males use to fight?

Answer 26

Weapons eg.

• horns
• antlers
• tusks