Biology (natural selection and genetic modification)

Question 1

Evidence for human evolution-

Answer 1

A fossil is any trace of animal or plant that lived a long time ago. They are most commonly found in rocks. Generally, the deeper the rock, the older the fossil.

By arranging fossils in chronological order, gradual changes in organisms can be observed.

Question 2

Evolution-

Answer 2

Is a gradual change in the characteristics of a species over time.

Question 3

Modern humans (homo sapiens)=
Homo erectus=
Homo habilis=
Australopithecus afarensis=
Ardipithecus ramidus=

Answer 3

195000 years ago to present.

1. 8 to 0.5 million years ago.
2. 4 to 1.4 million years ago
3. 9 to3.0 million years ago.
4. 4 million years ago.

Question 4

Genetic variation-

Answer 4

The characteristics of individuals vary (due to differences in genes)

Question 5

Natural selection-

Answer 5

By chance, the variations of some individuals make them better at coping with the change than others, and more likely to survive (also called ‘survival of the fittest’).

Question 6

Inheritance-

Answer 6

The survivors breed and pass on their variations to their offspring. So the next generation contains more individuals with the ‘better-adapted variations’

Question 7

Classification - 5 kingdom.

Answer 7

Animals- fish, mammals, reptiles, etc.
Plants- grasses, trees, etc.
Fungi- mushrooms and toadstools, yeast.
Prokaryotes- all single-called organisms without a nucleus
Protists- eukaryotic single-called organisms, e.g. algae.

Question 8

Classification- 3 kingdoms

Answer 8

Archaea- organisms in this domain look similar to bacteria but are actually quite different - as differences in their genetic sequences show. They were first found in extreme places such as hot springs and salt lakes.
Bacteria- this domain contains true bacteria like E.coli and staphylococcus.
Eukarya- this domain includes a broad range of organisms including fungi, plants, animals and protists.

Question 9

Selective breeding

Answer 9

When humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population.

Organisms are selectively bred for example:
Animals that produce more meat or milk
Crops with disease resistance
Dogs with a good, gentle temperament.
Plants that produce bigger fruit.

Question 10

Genetic engineering-

Answer 10

Genetic engineering involves changing the DNA of one organism (its genome), often by inserting genes from another. This creates genetically modified organisms (GMOs)

Question 11

What is one risk of selective breeding.

Answer 11

Alleles that are not selected become rare or disappear. So alleles that might be useful in the future are no longer available.

Question 12

Scientists use restriction enzymes to cut a useful gene out out of an organisms DNA.

Answer 12

Small circles of DNA are called plasmids.