Unit 2: Key Area 4 - Sex and behaviour

Question 1

Compare the number of gametes produced by sperm and eggs

Answer 1

Sperm produces millions of gametes constantly whereas a egg produces only one gamete a month

Question 2

Compare the size of gametes produced by sperm and eggs

Answer 2

Sperm produces a smaller gamete and an egg produces a larger gamete

Question 3

Compare the structure of gamete for sperm and egg

Answer 3

check flashcard

Question 4

Compare the chances of reproductive success for males and females and why

Answer 4

Males have higher chances of reproductive success as they produce more gametes and smaller gametes.
Whereas
Females have lower chances reproductive success as they produce less eggs and larger gametes

Question 5

Compare the chances of passing on genes for males and females and why

Answer 5

Males have higher chances of passing on genes as there is no investment needed.
Whereas
Females have lower chances passing on genes as they invest in the egg structure in non-mammals or in the uterus and during gestation in mammals.

Question 6

what is an advantage and disadvantage of parental investment

Answer 6

Parental investment is costly but increases the probability of production and survival of young

Question 7

What are is classification of r-selected (r-strategists) and K-selected (K-strategists) organisms based on

Answer 7

Classification of r-selected (r-strategists) and
K-selected (K-strategists) organisms are based
on the level of parental investment in offspring and number of offspring produced

Question 8

Compare the characteristics of r-selected species and K-selected species

Size

Answer 8

Characteristics of r-selected species:
smaller

Characteristics of K-selected species:
larger

Question 9

Compare the characteristics of r-selected species and K-selected species

Life span

Answer 9

Characteristics of r-selected species:
have a shorter generation time

Characteristics of K-selected species:
live longer

Question 10

Compare the characteristics of r-selected species and K-selected species

Mature time

Answer 10

Characteristics of r-selected species:
mature more rapidly

Characteristics of K-selected species:
mature more slowly

Question 11

Compare the characteristics of r-selected species and K-selected species:

Timing of first reproduction

Answer 11

Characteristics of r-selected species:
reproduce earlier in their lifetime

Characteristics of K-selected species:
reproduce later in life

Question 12

Compare the characteristics of r-selected species and K-selected species

How many offsprings produced per reproductive period

Answer 12

Characteristics of r-selected species:
produce a larger number of smaller offspring

Characteristics of K-selected species:
produce relatively few larger offsprings

Question 13

Compare the characteristics of r-selected species and K-selected species

How many times do they reproduce in a lifetime

Answer 13

Characteristics of r-selected species:
reproduces often only once

Characteristics of K-selected species:
reproduce many times

Question 14

Compare the characteristics of r-selected species and K-selected species

Level of parental care

Answer 14

Characteristics of r-selected species:
limited parental care

Characteristics of K-selected species:
high level of parental care

Question 15

Compare the characteristics of r-selected species and K-selected species

Likelihood of reaching adulthood

Answer 15

Characteristics of r-selected species:
most offspring will not reach adulthood

Characteristics of K-selected species:
many offspring have a
high probability of surviving to adulthood

Question 16

Compare the characteristics of r-selected species and K-selected species

Energy input

Answer 16

Characteristics of r-selected species:
small energy input

Characteristics of K-selected species:
larger energy input

Question 17

Compare the environment of r-selected species and K-selected species

Answer 17

r-selection tends to occur in unstable environments where the species has not reached its reproductive capacity, whereas K-selection tends to occur in stable environments

Question 18

Comparison of costs and benefits of external and internal fertilisation

Answer 18

External fertilisation
Benefits:
-very large numbers of offspring can be produced
Costs:
- many gametes predated or not fertilised
- no or limited parental care
- few offspring survive

Internal fertilisation
Benefits:
- increased chance of successful fertilisation
- fewer eggs needed
- offspring can be retained internally for protection
and/or development
- higher offspring survival rate
Costs:
- a mate must be located, which requires energy expenditure
- requires direct transfer of gametes from one partner to another

Question 19

What are mating systems based on

Answer 19

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

Question 20

What are the different types of mating systems

Answer 20

• polygamy
• polygyny
• polyandry
• monogamy

Question 21

Define a Monogamy mating system

Answer 21

Monogamy: the mating of a pair of animals to the exclusion of all others

Question 22

Define a Polygamy mating system

Answer 22

Polygamy: individuals of one sex have more than one mate

Question 23

Define a Polygyny mating system

Answer 23

Polygyny: one male mates exclusively with a group of females

Question 24

Define a Polyandry mating system

Answer 24

Polyandry: one female mates with a number of males in the same breeding season

Question 25

What do many animals have when choosing a mate

Answer 25

Many animals have mate-selection courtship rituals

Question 26

What is a successful courtship behaviour in birds and fish a result of

Answer 26

Successful courtship behaviour in birds and fish can be a result of species-specific sign stimuli and fixed action pattern responses

Question 27

Why is sexual selection important

Answer 27

Sexual selection selects for characteristics that have little survival benefit for the individual, but increase their chances of mating

Question 28

What do many species exhibit as a product of sexual selection

Answer 28

Many species exhibit sexual dimorphism as a product of sexual selection

Question 29

How is sexual dimorphism expressed in most cases

Answer 29

Females are generally inconspicuous; males usually have more conspicuous markings, structures and behaviours.

Question 30

How is sexual dimorphism expressed in some cases

Answer 30

Reversed sexual dimorphism occurs in some species

Question 31

What does female choice involve

Answer 31

Female choice involves females assessing honest signals of the fitness of males

Question 32

Describe honest signals

Answer 32

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 33

Describe what happens at a lek

Answer 33

In lekking species, males gather to display at a lek, where female choice occurs
Some bird species exhibit lekking behaviour. Dominant males occupy the centre of the lek, with subordinates and juveniles at the fringes as ‘satellite’ males. During the display, female choice occurs.

Question 34

Describe male to male rivalry

Answer 34

Males will fight for dominance and access to females, often using elaborate ‘weapons’ such as antlers, tusks, horns.

Question 35

what does success in male to male rivalry result in

Answer 35

Success in male-male rivalry through conflict (real or ritualised), increases access to females for mating