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Biology paper 2 - gcse > Topic 6 - Variation and Evolution > Flashcards

Topic 6 - Variation and Evolution Flashcards

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1
Q

Define the term Variation (1)

A

All the differences in the characteristics of individuals in a population

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2
Q

Define and give an example of genetic variation

A

Genetic variation (combination of genes from two parents)
e.g eye colour , blood group, inherited disorders

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3
Q

Define and give an example of environmental variation

A

variation caused by environmental factors
e.g yellow leaves, how tanned you are

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4
Q

Define Mutation

A

Changes to the sequence of bases in DNA

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5
Q

When do scientists believe life on Earth first began

A

3,000,000 years ago

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6
Q

What was Charles Darwin’s Theory? “survival of the fittest”

A

Organisms with the most suitable characteristics, for the environment, would be more successful competitors and would be more likely to survive

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7
Q

Define Natural Selection

A

The organisms with the most suitable characteristics are more likely to survive and reproduce, beneficial alleles are then passed on to the offspring

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8
Q

Define Evolution

A

A change in the inherited characteristics of a population over time through a process of natural selection

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9
Q

Explain 3 ways why Charles Darwin’s book “the origin of the species” 1859 was controversial

A

• It went against religious beliefs about how life on Earth first developed (God)

• There wasn’t enough evidence to convince scientists

• He didn’t have any explanation for why new characteristics appeared or how they were passed on to offspring

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10
Q

Define Selective breeding

A

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

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11
Q

What is the negative of selective breeding ?

A

• Reduction in the gene pool (number of different alleles)

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12
Q

Explain the selective breeding process (4)

A

1) From your existing stock select the ones which have the characteristics you are after
2) Breed them with eachother
3) Select the best of the offspring and breed them together
4) Continue this process over several generations, as the desirable trait will get stronger and stronger
5) Eventyally all offspring will have the characteristic

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13
Q

Explain what a gene is and it’s role

A

Genes are sections of DNA on a chromosome. Each gene codes for the amino acid sequence of a specific protein

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14
Q

What are the benefits of GM crops (genetically modified)

A

produce a greater yield and resistant to disease or insect attack

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15
Q

Explain the main steps in genetic engineering

A

1) First we identify the gene we want to transfer

2) Use enzymes to isolate the gene

3) transfer gene into a small circle of DNA (plasmids)

4) Transfer the desired gene into the cells of the targeted organism

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16
Q

What should be done if genetic engineering is done in animals

A

If done in animals they should do it at and early embryo stage, this is to make sure all of the cells receive the transferred gene and then develop with characteristics we want

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17
Q

What are the two ways you can clone plants

A

Cuttings
Tissue Culture

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18
Q

What is the process of cloning plants by “cuttings” (small number)

A

A small piece of plant is removed and the end is dipped in rooting powder (contains plant hormones encourages plants to develop roots)

• genetically identical clones of the starter plant is produced

19
Q

What is the process of cloning plants by tissue culture

A

• Take a plant that we want to clone and divide the plant into hundreds of tiny pieces

• Each piece contains a small number of cells

• Small groups of cells are then incubated with plant hormones

20
Q

What should the conditions be when cloning plants

A

Conditions should be sterile because we do not want to introduce any microorganisms

21
Q

What are the two ways to clone animals

A

Embryo transplants
Adult Cell cloning

22
Q

Explain the process of Embryo Transplants

A

• We start with the sperm and egg cell from an animal with characteristics we want

• Fertilisation produces a fertilised egg

• Allow the fertilised egg to develop to an early stage embryo

• use a glass rod to split this embryo into two

• Transplant embryos into host mothers

• When the animals are born we get two identical offspring

23
Q

What is the problem with embryo transplants (animal cloning)

A

Because we start with the sperm and the egg we cannot be certain that the offspring will have the characteristics we want

24
Q

Explain the process of Adult Cell Cloning

A

• Start by removing a cell from the adult we want to clone.

• Then remove the nucleus

• Take an unfertilised egg cell from the same species

• Then removed nucleus from unfertilised egg and throw it away

• Now insert the nucleus from original adult body cell into empty egg cell

• Then give egg cell and electric shock (egg divide to form an embryo)

• The embryo cell contains same genetic information as the adult cell

• Once embryo has developed into a ball of cells it’s inserted into the womb of an adult female to continue developing.

25
Q

How do new species form

A

• When a geographical barrier changes course and separates population into two groups.

• There will be no interbreeding between the organisms

• Over time natural selection will favour different alleles on the two sides of the island

• Any mutations that occur cannot spread between the two populations

• Over many generations, two population of organisms will begin to change

• Geographical barrier changes course again and the two populations can mix

• At this point the phenotypes of the two populations or organisms are so different they can no longer reproduce to make fertile offspring.

TWO DIFFERENT SPECIES

26
Q

Define Alleles

A

different versions of a gene

27
Q

What did Mendel say

A

Menedel said that two characteristics are determined by inherited units

28
Q

What are the 3 ways fossils are formed

A

1) Gradual replacement of minerals
2) From Casts and Impressions
3) Preservation in places where no decay happens

29
Q

Explain how gradual replacement by minerals can form fossils

A

1) teeth,shells bones can last a long time when buried

2) They’re eventually replaced by minerals as they decay, forming a rock-like substance shaped like the original hard part

3) The surrounding sediments also turn to rock

30
Q

Explain how casts and impressions form fossils

A

• When an organism is buried in a soft material like clay
• The clay later hardens and the organism decays leaving a cast of itself.

• Footprints can be pressed into materials when they are soft leaving an impression when it hardens

31
Q

Explain how preservation where no decay happens forms fossils

A

• In amber and tar pits there’s no oxygen or moisture so decay microbes can’t survive

• In glaciers it’s too cold for the decay microbes to work

• Pest boys are too acidic for decay microbes

32
Q

What are some ways species can become extinct

A

Catastrophic event
New disease
Weather patterns
New predator

33
Q

How often does bacteria reproduce

A

every 30 minutes

34
Q

When did the treatment for bacteria first be discovered

A

1940’s penicillin

35
Q

Antibiotics…

A

KILL BACTERIA

36
Q

Name and antibiotic resistant bacteria

A

MRSA

37
Q

What are 3 ways we can reduce the development of antibiotic resistant strains of bacteria

A

• Doctors should not prescribe antibiotics inappropriately (no virus)

• Patients should be certain to complete their course of antibiotics, (as if all not killed, some may mutate)

• We should restrict the use of antibiotics in farming

38
Q

How does antibiotic resistant happen ?

A

• Once an antibiotic is used all bacteria is killed apart from one antibiotic resistant bacteria.

• The antibiotic resistant strain survives and reproduces

• Over time the population of the resistant strain rises

• The strain now spreads (because people and not immune to it and there is no effective treatment)

39
Q

What happened in 1700’s

A

Linnaeus began to classify species in different categories based on their structure and characteristics

40
Q

What are the two kingdoms

A

Animal
Plant

41
Q

What’s the order of the Classification system (King Philip Came Over For Good Soup)

A

Kingdom
Phylum
Class
Order
Family
Genus
Species

42
Q

Every organism is named from their

A

Genus and Species

(Binomial system)

43
Q

What is the three domain system

A

Worse compared biochemistry with different organisms

44
Q

What are the 3 organisms in the three domain system

A

Archae
True Bacteria
Eukaryota

Biology paper 2 - gcse (2 decks)

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