Reproduction

Question 1

Define sexual reproduction

Answer 1

Is where a genetic information from two organisms (Mother&Father) is combined to produce offspring which are genetically different to either parent.

Question 2

What do the mother and father produce in sexual reproduction?

Answer 2

Gametes by meiosis - Egg and sperm cells in animals

Question 3

How many chromosomes in each gametes in humans contain?

Answer 3

23 chromosomes - half the no. of chromosomes in a normal cell

Question 4

What do the egg and sperm cell do?

Answer 4

Fuse together by fertilisation to form a cell with the full number of chromosomes

Question 5

What do offspring inherits from both parents?

Answer 5

Features - receives a mixture of chromosomes from its mum and dad

Question 6

What does the mixture of genetic information produce?

Answer 6

Variation in the offspring

Question 7

Give an example of an organism that can reproduce

Answer 7

Flowering plants

Question 8

Explain how flowering plants can reproduce

Answer 8

They have egg cells, but their version of sperm is known as pollen

Question 9

What is required in asexual reproduction?

Answer 9

One parent cell - so the offspring are genetically identical to the parent

Question 10

What does asexual reproduction happen by?

Answer 10

Mitosis - an ordinary cell makes a new cell by dividing in to 2

Question 11

Define the term clone

Answer 11

The new cell has exactly the same genetic information as the parent cell

Question 12

Give examples of organism that reproduces asexually

Answer 12

Bacteria
Some plants
Some animals

Question 13

What do gametes have?

Answer 13

One copy of each chromosomes

Question 14

Why do gametes only have one copy of each chromosome?

Answer 14

When gamete fusion takes place you get the right amount of chromosomes again - two copies of each

Question 15

How do you make gametes which only have half the original number of chromosomes?

Answer 15

Cells divide by meiosis

Question 16

What does meiosis involve?

Answer 16

Two cell divisions

Question 17

Where does this occur in humans?

Answer 17

Only happens in the reproductive organs

Question 18

Give examples where they occur in humans

Answer 18

Ovaries - Females

Testes - Males

Question 19

Explain what happens in Meiosis

Answer 19

Duplicates DNA = two armed chromosomes
One arm of each chromosome = exact copy of other arm -Replicate
Arrange themselves into pairs

1st division - chromosome pairs line up in the centre of the cell, pairs pulled apart - new cell only has one copy of each chromosome

2nd division - chromosomes line up again in the centre of the cell. Arms of chromosomes pulled apart

= 4 gametes, single set of chromosomes
Each gamete is genetically diff. = shuffled up and at random each only gets half chromosomes

Question 20

How after two gametes have fused during fertilisation?

Answer 20

Resulting new cell divides by mitosis to make a copy of itself

Question 21

What does mitosis produce when it repeats its self many times?

Answer 21

Lots of new cells in an embryo

Question 22

What happens as the embryo develops?

Answer 22

These cells then start to differentiate into the different types of specialised cell that make up a whole organism

Question 23

What does the offspring from sexual reproduction have?

Answer 23

A mixture of two sets of chromosomes

Question 24

What does the organism inherit?

Answer 24

Genes and features from both parents, which produces variation in the offspring

Question 25

What does variation increases?

Answer 25

The chance of species surviving change in the environment

Question 26

Explain the change in the environment that could kill some individuals

Answer 26

It's likely that variation will have led to some off the offspring being able to survive in the new environment = survival advantage

Question 27

Define natural selection

Answer 27

Individuals with characteristics that make them better adapted to the environment have a better chance of survival, they are more likely to breed successfully and pass the genes for the characteristics on.

Question 28

What cab we do with selective breeding?

Answer 28

To speed up natural selection which allows us to produce animals with desirable characteristics

Question 29

Define selective breeding

Answer 29

Is where individuals with a desirable characteristic are bred to produce offspring that have the desirable characteristic too.

Question 30

Explain how we can increase food production

Answer 30

By breeding animals that produce a lot of meat

Question 31

Give advantages of asexual reproduction

Answer 31

Needs to be one pair Uses less energy - organisms don't have to find a mate Faster Many identical offspring can be produced in favourable conditions