Unit Two : Variation and Sexual Reproduction

Question 1

What is the definition of a sequential hermaphrodite ?

Answer 1

Such as jellyfish , these are organisms which are born as one sex and may change to the other sex at some point during their life.This usually occurs if reproductive success is more likely.

Question 2

Aside from genetic control , what other factor can sex determination be under the influence of and give an example of an organism that is influenced by this factor ?

Answer 2

Environmental control

Nile crocadiles

Question 3

What is the gender of Nile offspring determined by ?

Answer 3

The temperature of egg incubation

Question 4

What are the specific temperature conditions that only produces female crocadiles ?

Answer 4

BELOW 31.7

ABOVE 34.5

Question 5

What is the name given to a gene that is not a sex chromosome ?

Answer 5

Autosome

Question 6

Why are males said to be heterogametic?

Answer 6

As their sex chromosomes are dissimilar (XY)

Question 7

In mammals,how is the sex determined ?

Answer 7

By the set of specific sex chromosomes X and Y

Question 8

Give some factors that might cause an organism to change sex ?

What is the underlying reason why organisms change sex ?

Answer 8

Size,competition and parasitic infection

To enable the occurrence of successful reproduction

Question 9

On comparison with asexual reproduction,sexual reproduction has two disadvantages, what are they ?

Answer 9

Half the population (males ) are unable to produce offspring
Each parent can only pass on half of their genetic material

Question 10

What is the main benefit of sexual reproduction and what does it allow the organism to do ?

Answer 10

Greater genetic variation

To adapt to changing conditions which may allow it to survive

Question 11

What are the requirements for asexual reproduction to be successful ?

Answer 11

Narrow and stable

Question 12

What is a advantage of asexual reproduction ?

Answer 12

When recolonising disturbed habitats it’s usually faster

Question 13

What term could be defined as asexual reproduction in plants such as bulbs or runners where the resulting offspring are genetically identical (clones) of their parents

Answer 13

Vegetative propagation

Question 14

What term can be defined as asexual reproduction in reptiles where offspring are produced in the absence of fertilisation that is found to be more common in cooler climates and low parasite diversity ?

Answer 14

Parthenogenesis

Question 15

Komodo dragons have been known to reproduce with out fertilisation(they are parthenogenesis organisms) how is this advantageous to the organisms ?

Answer 15

As should the females become isolated,they can still reproduce successfully

Question 16

What is the definition of a simultaneous hermaphrodites ?

Answer 16

These are organisms with both male and female reproductive organisms such as earthworms

Question 17

Sexual investment
A far greater investment is made by females due to the production of a ________ number of larger ______. As a result their chance of reproductive success is….

Answer 17

Lower
Gametes
Lower

Question 18

What are sessile organisms ?

Answer 18

Those fixed to a surface and therefore cannot move,such as barnacles and plants.

Question 19

Explain how corals achieve sexual reproduction ….

Answer 19

Stages in their life cycle are mobile - especially in the larval stage of corals.Clouds containing millions of gametes are released into the water simultaneously,increasing chance of successful fertilisation.The larvea that results from fertilisation are motile for a period of time.

Question 20

Slow moving and ____ organisms are often …. Or employ parasitism as a reproductive strategy

Answer 20

Hermaphroditic

Question 21

In plants,what two factors play a vital role in successful pollination

Answer 21

Insects and wind

Question 22

What is internal fertilisation ?

Answer 22

The process whereby the sperm and egg nuclei fuse inside the female

Question 23

Why is external water essential for external fertilisation ?

Answer 23

As it prevents the gametes from drying out and to provide a medium for sperm to swim to the eggs

Question 24

What type of behaviour is important to external fertilisation because timing is crucial to ensure that mature sperm and ripe eggs meet.

Answer 24

Courtship

Question 25

What type of fertilisation requires highly advanced reproductive systems ?

Answer 25

Internal

Question 26

Give examples of two stimuli that may lead to organisms releasing their gametes ?

Answer 26

Environmental such as temperature of day length

Chemical from one individual releasing their hormones may induce others to release their gametes as well .

Question 27

Complete the passage .
All species produce ______ offspring that survive to reproduce.Species with external fertilisation usually produce _____ numbers of gametes ,but the proprtion that are successfully fertilised,survive and develop further is often quite ______.Internal fertilisation usually produces ______ offspring;however,success is usually ______.Embryos are offered greater protection and parental care is ________.

Answer 27

More
Enormous 
Small
Fewer
Greater
High

Question 28

Give three examples of protection that requires a greater input of energy ….

Answer 28

Resistant egg shells
Development of the embryo within the female parent
Parental care or eggs and offspring

Question 29

Even though parental investment is costly why is it important ?

Answer 29

Increases the chance that the young will survive

Question 30

In a stable environment,organisms tend to produce what number of offspring ?and what type of offspring ?

Answer 30

Smaller number

Rather ‘expensive’ young - thus lots of energy will be invested in caring for each one

Question 31

Organisms can be classed as r-selected and k-selected based on their ….. and life history

Answer 31

Reproductive strategy

Question 32

Describe what the term optimal reproduction means?

Answer 32

The trade off between the number and quality of current offspring versus potential future offspring

Question 33

What is the definition of monogamy ?

Answer 33

Species where bonds are formed between one male mating with one female.This relationship may be described as monogamous .

Question 34

What does the term sexual dismophorism describe ?

Answer 34

When males and females of the same species have a very different physical appearance ,often in terms of colour and size which is a results of sexual selection

Question 35

Why is it important that females are usually inconspicuous?

Answer 35

Since she may carry and protect the young,an ability to camouflage or blend in will increase her and her offsprings chance of survival

Question 36

Smaller males may employ what type of behaviour and still see equal success at gaining access to the female and reproducing …..

Answer 36

Sneaking behaviour

Question 37

Describe what the process of lekking involves ….

Answer 37

In a number so birds and insect species,males display communally in a small area called a LEK.Females then visit the lek and choose among displaying males by assessing weather signals are ‘honest’ .Healthy plumage represents good condition as it indicates low parasite density.Healthy plumage can be used to infer that the male has strong genes against parasite and diseases

Question 38

These sneaking males are often called ….

Answer 38

Satellite males

Question 39

Describe the process of imprinting ….

Answer 39

An irreversible process in young birds where they fixate on a larger living thing for protection and nurturing - may affect mate choice later in life

Question 40

Successful courtship behaviour is often the result of species-specific sign stimuli …. Give a few examples of these signals

What is the advantage of species specific sign stimuli ?

Answer 40

Giving off chemicals
Making sounds or certain displays

This allows species to mate when most fertile- increasing the chance of successful reproduction.

Question 41

Species- specific signals are said to be what ?

Answer 41

Innate ( existing since birth) and therefore instinctive