Reproduction And Inheritance

Question 1

What does diploid mean and what is the number for the human body

Answer 1

Diploid means they have two copies of each chromosome, arranged in pairs
A human cell nucleus contains 46 chromosomes so the diploid number for humans is 46

Question 2

Name the four different bases found in DNA

Answer 2

Adenine (A)
Cytosine (C)
Guanine (G)
Thymine (T)

Question 3

How do bases found in DNA pair up

Answer 3

The bass are pairs and they always pair up in the same way it’s always:
A-T and C-G

Question 4

Why does sexual reproduction result in offspring that are genetically different from either parent

Answer 4

Sexual reproduction involves the fusion of male and female gametes. Because there are two parents, the offspring contain a mixture (23 chromosomes from each) of their parents genes

Question 5

Describe how and where meiosis takes place

Answer 5

In humans meiosis only happens in the reproductive organs (ovaries and testes)
Division 1:
1) before the cells begin division it duplicates its DNA so there’s enough for each new cell (each arms are exact copies of one another)
(Don’t understand rest)

Question 6

Name male and female reproductive parts of the flower

Answer 6

Male:
Stamen- containing anther and filament
Female:
Carpel- containing ovary, style and stigma

Question 7

Define pollination

Answer 7

Pollination is the transfer of pollen from an anther to a stigma, so that the male gametes can fertilise the female gametes in sexual reproduction

Question 8

Give three differences between plants that are pollinated by insects and ones that are wind pollinated

Answer 8

Insect pollinated:
Bright colour petal
Scented flowers and nectaries
Big sticky pollen grains 
Stigma is also sticky 
Wind pollinated 
Small dull petals
No next aired 
Lots of pollen (small and light)
Long filament that hang anthers outside flower so wind can blow pollen away 
Large feathery stigma to catch pollen, often hangs outside the flower too

Question 9

Define fertilisation

Answer 9

Fertilisation is the fusion of gametes

Question 10

Explain how the pollen gets from the stigma to the ovary

Answer 10

1) pollen grain lands on the stigma of a flower
2) pollen tube grows out of pollen grain and down through the style to the ovary and into the ovule
3) the nucleus from the male gamete moves down the tube to join with a female gametes in the ovule
4) fertilisation occurs then mitosis divides the zygote to form an embryo

Question 11

What 3 conditions are needed for seed germination

Answer 11

1) water - to activate the enzymes and break down the food reserves in the seed
2) oxygen - for respiration which provides the energy for growth
3) a suitable temperature - for the enzymes inside the seed to work

Question 12

How do germinating seeds get energy from food stores

Answer 12

1) a developed seed contains an embryo and a store of food reserves, wrapped in a hard seed coat
2) when a seed starts to germinate, it gets glucose for respiration
3) once the plant has grown enough to produce green leaves, it can get its own food for energy from photosynthesis

Question 13

Give an example of a plant that reproduces asexually and briefly describe how it happens

Answer 13

Strawberry plants

1) the parent strawberry plant send out runners - fast growing stems that grow out sideways, just above the ground
2) the runners take root at various points (a short distance away)and new plants start to grow
3) the new planes are clones of the parents

Question 14

Describe how to make plant clones from cuttings

Answer 14

1) gardeners can take cuttings from good parent plants to produce genetically identical copies
2) cuttings are taken each with a new bud on
3) the cuttings are kept in moist conditions until they are ready to plant
4) these plants can be produced quickly and cheaply

Question 15

Where are sperm and the ova made in the human reproductive system?

Answer 15

Sperm are made in the testes

Ova are made in the ovaries

Question 16

What secondary characteristic does testosterone trigger in makes

Answer 16

1) extra hair oh face and body
2) muscles to develop
3) deepening voice

Question 17

What secondary characteristics doers oestrogen in females

Answer 17

Extra hair underarms and pubic area
Hips widen
Breasts
Periods

Question 18

Describe the four stages of the menstrual cycle

Answer 18

Stage 1: day 1 is when bleeding starts - the uterus lining breaks down for about 4 days
Stage 2: the uterus lining builds up again from day 4-14 into a thick spongy layer full of blood vessels, ready to receive egg
Stage 3: ovum develops and is released from dat 1:
Stage 4: the wall is then maintained for 14 days until day 28

Question 19

What role do oestrogen and progesterone play in the menstrual cycle

Answer 19

Oestrogen causes the lining of the uterus to thick and grow. It also stimulates the release of an ovum

Progesterone maintains the lining of the uterus. When the level of progesterone falls, the lining breaks down

Question 20

What is the function of amniotic fluid in pregnancy

Answer 20

Amniotic fluid protects baby against knocks and bumps

Question 21

What does it mean if you are homozygous for a particular trait

Answer 21

If you’re homozygous for a trait you have two alleles the same for that partially gene eg CC or cc

Question 22

What are codominant alleles

Answer 22

Neither allele is recessive so you show characteristics from both alleles eg blood group A or B but blood groups AB

Question 23

Which two chromosomes determine where you are male or female p

Answer 23

There are 23 matched pairs of chromosomes in every human body cell. The 23rd pair is labelled xx or xy. They’re the two chromosomes that decide whether you turn out male or female

Question 24

List four features of animals which aren’t affected at all by their environment, and three which are

Answer 24

Aren't affected:
Eye colour
Hair colour 
Inherited disorder 
Blood group 
Affected:
Growth 
Intelligence 
Spouting ability

Question 25

What is the theory of evolution

Answer 25

Life began as simple organisms from which more complex organisms evolved

Question 26

What is a mutation

Answer 26

Mutations are rare random changes to the genetic code/ organism’s DNA

Question 27

Give and example of how a genetic mutation could be a) harmful b) beneficial

Answer 27

A) harmful- mutations occur in reproductive cells, the offspring might develop abnormally or die. If a mutation occurs in body cells the mutant cells stat to multiply in an uncontrolled way and invade other part of the body (cancer)
B) beneficial - mutations can be beneficial and give an organism a survival advantage, so it can live on in conditions where the others die. This is natural selection. Eg a mutation in bacterium might make it resistant to antibiotics

Question 28

What is a Superbug

Answer 28

Superbugs are resistant to most known antibiotics such as MRSA

Question 29

What is a gene

Answer 29

A short section of DNA