unit 2 AOS 2

Question 1

Asexual reproduction

Answer 1

type of reproduction that does not require the fusion of gametes, where offspring arise from a single parent and are genetically identical to that parent

- New cells or organisms are produced without the fusion of gametes 

- Occurs in both eukaryotic  and prokaryotic organisms 

All cells produced are genetically identical to the parent cell

Question 2

Reproduction

Answer 2

Reproduction is the creation of a new generation of single cells in single-celled or multi-cellular organism

Question 2

advantages of asexual reproduction

Answer 2

• Faster process - increased population
• Doesn’t require fertilisation

Doesn’t require fusion of gametes

Question 2

disadvantages of asexual reproduction

Answer 2

• No genetic variation - no protection from diseases (one person gets it, they all get it)

Question 3

asexual Reproduction methods:

Answer 3

Binary fission

Budding

Spore formation

Fragmentation

vegetative propagation

Parthenogenesis

Question 3

binary fission

Answer 3

division of a parent nucleus to produce two new daughter cells

• in bacteria

Question 4

budding

Answer 4

A new organism or parts of an organism develop from an outgrowth of the parent

• in patatoes

Question 5

Spore formation

Answer 5

Hardly capsules that contain the DNA instruction needed to produce a new plant

Question 6

Fragmentation

Answer 6

New individuals are generated from fragments

An organism breaks into smaller parts, which develop into new organisms. The daughter organisms are smaller than the parent organisms

• in starfishes

Question 7

vegetative propagation

Answer 7

Vegetative propagation - where a detached part of a plant develops into a new individual

• in a mint plant

Question 8

Parthenogenesis

Answer 8

Reproduction from an egg without fertilisation (virgin birth)
Can only occur in females

Involves the development of an egg into a new organism

• in hammerhead sharks

Question 9

what is external fertilisation

Answer 9

Union of sperm and egg occurring outside the body of the female parent

occurs when animals release their gametes into the external environment so that fertilisation occurs outside the body of females

- E.g. for frogs: the male clasps the female tightly and when the female releases her eggs into the water, the male releases sperm over the eggs. The eggs are suspended on a raft of bubbles

Question 10

what is Internal fertilisation

Answer 10

Union of sperm and egg occurring inside the body of the female parent

occurs when males deliver sperm directly into the reproductive tract of females so that fertilisation of eggs occurs inside the body of females

Question 11

what is Sexual reproduction

Answer 11

a specific reproductive strategy that involves the fusion of two haploid gametes, a process known as fertilisation, to form a single, genetically unique zygote

Question 12

advantaghes of sexual reproduction

Answer 12

• Increases genetic diversity of a population by allowing recombinant offspring
• Improving disease resistance by promoting the presence of different alleles

Combining the genetic material from two gametes reduces the chances of an offspring inheriting a genetic disorder that might be carried by one parent

Question 13

disadvantages of sexual reproduction

Answer 13

• The cost male progeny
• The time, energy and resources it takes to attract and find a mate
• The risk of transferable diseases associated with sexual intercourse
• The risk of losing an offspring to outside influences such as embryo damage

Question 14

features of internal fertilisation

Answer 14

· It has an energy cost of finding, attracting and securing a mate

· It has the benefit of increasing the chances of the gametes meeting, and therefore increases the chances of fertilisation 

· It occurs in some aquatic organisms as well as in terrestrial organisms 

· All terrestrial animals use internal fertilisation, except for amphibians, such as frogs and toads that mate in the water

Question 15

Genetic diversity

Answer 15

The production of gametes via meiosis results in genetic variation due to independent assortment of chromosomes and crossing over

- Organisms produced via sexual reproduction receive half of their genetic information from each parent

- Genetic diversity is very important for maintaining the health and longevity of a species

- It is maintained in a variety of ways, including sexual reproduction and asexual reproduction

Question 16

Differences between asexual and sexual reproduction

Answer 16

Asexual reproduction:
One parent contributes genetic material

Daughter cells are usually identical to the parent cell

No exchange of genetic material

Chromosomes are not assorted

Less energy requires

Does not affect genetic diversity

sexual reproduction:
Two parents contribute genetic material

Daughter cells are different to the parent cells

Exchange of genetic material through crossing over of chromosomes

Chromosomes are assorted independently

Energy invested in finding a mate

Increases genetic diversity in a population