B1 Enviroment And Evolution

Question 0

Explain generic variation.

Answer 0

An organisms characteristics are determined by the genes inherited from their parents. These are passed on by gametes.
Generic variation is created when the genes from the mother and farther are mixed together. Because of this, on identical twins are the same.

Question 1

What is variation?

Answer 1

When organisms of the same species are different. There is genetic and environmental variation.

Question 2

Name some characteristics that are only determined by genetics?

Answer 2

Eye colour, blood group and inherited disorders.

Question 3

Explain environmental variation.

Answer 3

It covers a wide range of differences. It can mean getting a tan, losing a limb or getting yellow leafs.
It is any difference that has been caused by the conditions something lives in.

Question 4

Which characteristics can be determined by genes and the environment ?

Answer 4

Body weight, height, skin colour, condition of teeth, academic or athletic and prowess.

Question 5

Describe the nucleus.

Answer 5

Found in most body cells.

It contains genetic information in the form of chromosomes.

Question 6

How many chromosomes in a human cell.

Answer 6

There are 23 pairs found in each human cell.

Question 7

What do chromosomes do?

Answer 7

Carry genes. Different genes control the development of different characteristics.

Question 8

What is a gene?

Answer 8

A short length of the chromosome which contains lots of DNA.

Question 9

What are alleles?

Answer 9

Different versions of the same gene that provide different characteristics.

Question 10

What is sexual reproduction?

Answer 10

It is when generic information from two parents is combined when their gametes join. The offspring will end up with 23 pairs of chromosomes and each pair will have one from the farther and one from the mother.
The genetic information will be mixed.

Question 11

Explain asexual reproduction.

Answer 11

There is only one parent. No gametes fuse and no generic variation. The offspring will be genetically identical to the parents.
This how plants and animals grow and heal.
This happens when a cell splits down the middle.

Question 12

How can plants be cloned with cuttings?

Answer 12

Gardeners can take cuttings from good parent plants and then plant them to produce genetically identical copies.
These can be made quickly a cheaply.

Question 13

How can plants be cloned with tissue cultures?

Answer 13

A few plant cells are put in a growth medium with hormones and then grown into new plants. These can be made quickly in very little space and can be grown all year.

Question 14

How can animal clones be made with embryo transplants?

Answer 14

Farmers may use this to clone a good bull or cow.
Sperm cells are taken from a good bull and egg cells from a good cow. A embryo is created with the two and it will split into more cells.
These cells will be taken apart and then impreganted in lots of other cows. All the calves born will be clones.
Hundreds of ideal offspring can be produced every year in this way.

Question 15

Explain adult cell cloning.

Answer 15

An unfertilised egg cell is taken and the nucleus is taken out. A complete set of chromosomes from an adult cell is taken and out into the empty egg. This adult will be cloned.
The egg cell is given an electric shock which makes the two parts fuse and it will start to divide.
When it is a ball of cells, it will be implanted into a surrogate mother which will give birth to the clone.

Question 16

What are the issues surrounding cloning?

Answer 16

It reduced the gene pool meaning there are fewer different alleles in a population. This means a whole population could be wiped out if a new disease appears.
Cloned animals might not be healthy. Dolly the sheep had arthritis which occurs in older sheep. We don’t know if this was because of the cloning.
If humans are going to be cloned any success might follow many failures like children born disabled.

Question 17

What are the positives of cloning?

Answer 17

It could help preserve endangered species.

It could lead to a greater understanding of the development of the embryo and of age related disorders.

Question 18

How can useful genes be taken from one organism and put in another?

Answer 18

An enzyme is used to cut an useful gene from an organisms chromosome.
Enzymes are then used to cut another organisms chromosomes and they are then used to insert the gene in.
This can be done to make bacteria that produce human insulin.

Question 19

What are some of the advantages or genetic enginering?

Answer 19

Genetic disorders like cystic fibrosis could be cured by inserting working genes. This is gene therapy.
Sheep have been engineered to produce substances like drugs in their milk that can used to treat human diseases.

Question 20

What are the advantages of GM crops?

Answer 20

They can increase yield of a crop making more food.
GM crops could be engineered so that they contain more nutrients to help the developing world.
They have all ready been grown and there have been few problems.
They can make their own herbicides and insecticides.

Question 21

What are the cons of GM crops?

Answer 21

Some say they will affect the number of weeds and flowers and the number of insects living around them which means a reduction in farmland diversity.
Some say people may develop allergies to them.
Transplanted genes may get out and into the natural environment. The Herbicide resistance gene may be picked up by weeds, creating a new super weed.

Question 22

What does the theory of evolution say?

Answer 22

3 billion years ago life on earth began as simple organisms from which all the more complex organisms evolved.

Question 23

If species have the same recent common ancestor, what does it mean?

Answer 23

They will have similar genes and characteristics. They will live in the same type of habitat and look similar.

Question 24

If different species in the same environment are found with the same characteristics, what does it mean?

Answer 24

They may be in competition with each other.

Question 25

What is natural selection?

Answer 25

Is causes evolution.
Individuals within a species show variation because of differences in genes. Mutation could also cause differences.
Individuals which characteristics that make them better adapted will mean they will survive and breed more.
The genes that are responsible for the useful characteristics are more likely to be passed on to the next generation.

Question 26

Why were the ideas of Darwin controversial at the time?

Answer 26

It went against common religious beliefs which said that God created everything.
Darwin couldn’t explain why useful characterises appeared or how they were passed on. Genes and mutations had yet to be discovered.
Some felt there wasn’t enough evidence as few had conducted similar studies.

Question 27

What did Lamarck think about life?

Answer 27

He said if characteristics were used a lot by an organism it would become more developed during its life time.
He believed that these acquired characteristics would be passed on to the next generation.

Question 28

Why was Lamarck’s idea dropped?

Answer 28

Experiments didn’t surrport his idea. If you dye a hamster pink the offspring will be normal coloured. It won’t have been passed on.
Genetics supported Darwin’s idea and they is more evidence.

Question 29

Why do scientists develop different hypotheses from the same observations?

Answer 29

They may have different beliefs(religious) they may have been influenced by different scientists or they may think differently.

Question 30

Define ecosystem.

Answer 30

A community and its habitat.

Question 31

Define community.

Answer 31

All the populations of different organisms that live together in a habitat.

Question 32

Define population.

Answer 32

All the members of a single species that live in a habitat.

Question 33

Define habitat.

Answer 33

The place where an organism lives.

Question 34

Why are lichen sensitive to pollution?

Answer 34

They absorb their nutrients from the rain so are effected if it is polluted.

Question 35

When did the first life start?

Answer 35

4.5 billion years ago.

Question 36

What are the advantages of using tissue cultures companies to taking cuttings?

Answer 36

More off spring from a single plant, less damage to the original plant.

Question 38

Why would some people be worried about producing GM animals?

Answer 38

The changed genes could transfer to other fish, it could affect the food chain or affect the changes animal itself.

Question 39

Why is only a small amount of light from the sun turned into energy in plants ?

Answer 39

Light is reflected, not absorbed by or misses chloroplasts, wrong wave length, photosynthesis is inefficient, some is lost in respiration.