Sex and Behaviour

Question 1

Why are eggs are much larger and fewer in number?

Answer 1

Due to the presence of an energy store

Question 2

Why do females make a greater sexual investment?

Answer 2

due to the production of a lower number of larger gametes.

Question 3

A far greater investment is made by females due to the production of a lower number of larger gametes. What effect does this have on their chance of reproductive success and the chance of passing on genes?

Answer 3

their chance of reproductive success is lower and the chance of passing on genes is reduced.

Question 4

In mammals, it is typically the female who have a relatively larger parental investment in producing each offspring. Why is this the case?

Answer 4

 Placental Nourishment
 Lactation – feeding the young
 Post-natal care and protection

Question 5

What are sessile organisms?

Answer 5

Sessile organisms are those that are fixed to a surface and therefore cannot move.

Question 6

How do slow moving and sessile organisms reproduce?

Answer 6

Slow moving and sessile organisms are often hermaphroditic or employ parasitism as a reproductive strategy. Barnacles, for example, are hermaphroditic. They use extremely long sex organs to reach another for the transfer of sperm.

Question 7

What can parental investment be? What benefit can it bring?

Answer 7

Parental investment is costly but increases the chance that young will survive.

Question 8

Give the characteristics of a r-selected species. (9)

Answer 8

Unstable environment 
Short maturation time
Short life span
Usually high death rate 
Many offspring produced per reproductive episode
Usually one reproduction in lifetime
Early in life - Timing of first reproduction
Small size of offspring or eggs
No parental care

Question 9

Give the characteristics of a k-selected species. (9)

Answer 9

Stable environment 
Long maturation time
Long life span
Usually low death rate
Few offspring produced per reproductive episode
Often several reproductions in lifetime
Later in life - Timing of first reproduction
Large size of offspring or eggs
Often extensive parental care

Question 10

What is a survivorship curve?

Answer 10

A survivorship curve is a graphic representation of the number of individuals in a population that can be expected to survive to any specific age.

Question 11

What is monogamy?

Answer 11

one male mating with one female

Question 12

What are the two types of polygamy? What do they mean?

Answer 12

Polygamy:

• Polyandry - One female and multiple males
• Polygyny – One male and multiple females

Question 13

What is courtship?

Answer 13

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

Question 14

What is sexual dimorphism?

Answer 14

Sexual Dimorphism is defined as any physical differences between males and females.

Question 15

What are the three main physical differences between males and females?

Answer 15

Size – Males are often larger than females.
Colouration – Females are inconspicuous, and males are very conspicuous using colour to display during courtship and territorial behaviour.
Secondary Structures – Males tend to have adornments such as antlers, ornate plumage or a mane.

Question 16

What is reverse sexual dimorphism?

Answer 16

Reverse sexual dimorphism is when the normally inconspicuous female is larger or more ornate than the male.

Question 17

Describe male-male rivalry.

Answer 17

Males demonstrate different strategies to gain access to females to ensure successful mating:
 Acquiring and defending territories and harems – engaging in direct conflict with other males – superior size and weaponry ensuring success – the alpha male approach.
 Adopting the role of a ‘sneaker’ or a ‘satellite’ male – not engaged in direct conflict – seeking alternative opportunities to mate.

Question 18

What does sneaking behaviour refer to?

Answer 18

Sneaking behaviour refers to a strategy that allows smaller, less threatening males to more stealthily access to a female partner, often avoiding alterations with dominant males.

Question 19

Who retains primary control over reproduction?

Answer 19

females

Question 20

What does male courtship and appearance provide females with?

Answer 20

Male courtship and appearance provides, females with honest signals of male fitness.

Question 21

What does an impressive courtship display or good appearance indicate?

Answer 21

An impressive courtship display or good appearance indicates a healthy male with a low parasite burden and the presence of advantageous genes – both indicators of ‘fitness’.

Question 22

What do females use honesty signals for?

Answer 22

Females use honesty signals to choose healthier males in order to increase their own fitness and reproductive success.

Question 23

What is lekking?

Answer 23

During the breeding season males cluster at a communal display area or lek – displaying and possibly fighting to attract females.

Question 24

What does lekking allow?

Answer 24

This allows female choice. Females observe the display enabling them to select the fittest male who they will then mate with.

Question 25

What can successful courtship in birds and fish can be a result of?

Answer 25

species- specific sign stimuli and fixed action pattern responses.

Question 26

What is imprinting?

Answer 26

Imprinting is an irreversible, developmental process that occurs during a critical time period in young birds.