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Biology AQA GCSE > Inheritance, Variation and Evolution > Flashcards

Inheritance, Variation and Evolution Flashcards

1
Q

What shape is DNA

A

Double helix

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2
Q

What are chromosomes

A

Long molecules of DNA

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3
Q

What is a gene and what does it do

A

A short section of DNA found on a chromosome that codes for a specific protein

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4
Q

What is the genome

A

The entire set of genetic material within an organism

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5
Q

Why is knowing the entire human genome useful

A

Can identify which genes are linked to different types of disease

Can identify which genes are linked to inherited diseases

Can use the genome to track the migration that humans took from Africa

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6
Q

What are the monomers for DNA

A

Nucleotides

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7
Q

What is a nucleotide made up of

A

Sugar
Phosphate
Base

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8
Q

Which bases pair up with each other

A

A + T
C + G

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9
Q

How many bases code for 1 amino acid

A

3

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10
Q

What do non-coding parts of DNA do

A

Control whether or not a gene is expressed

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11
Q

How does protein synthesis happen

A

DNA Unzips
mRNA copies the code from the bases
moves into ribosomes in the cytoplasm
A tRNA carrier molecule carrying an amino acid
complementary bases attach
joins amino acid chain
then folds up uniquely to form a protein

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12
Q

Uses of proteins

A

Enzymes
Hormones
Structural proteins eg collagen

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13
Q

What is a mutation

A

A random change in an organism’s DNA

Can sometimes be inherited

Most mutations have little to no affect

A mutation in non-coding DNA may affect which genes are expressed

However some mutations can seriously affect a protein as it can change the way the fold up, meaning the substrate may no longer be able to bind to it

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14
Q

What are the different types of mutation

A

Insertions
Deletions
Substitutions

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15
Q

How many chromosomes does each gamete have in humans

A

23 (half)

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16
Q

What type of cell(in terms of difference) does sexual reproduction produce

A

Genetically different cells

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17
Q

What type of cells (in terms of difference) does asexual reproduction produce

A

Genetically identical cells

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18
Q

How are gametes produced

A

Meiosis

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19
Q

What happens in meiosis

A

Genetic information duplicates

In the first division the chromosome pairs line up at the centre of the cell

The pairs are pulled apart so each new cell only has 1 copy of each chromosome
(some of the father’s and some of the mother’s go into each cell)

In the second division the chromosomes line up again in the centre of the cell and the arms of the chromosomes are pulled apart

You end up with 4 gametes each with only a single set of chromosomes in it

Genetically different

20
Q

What are the pros and cons of sexual reproduction

A

Pros:
Variation in offspring

Cons:
Slow(er)
Requires 2 organisms

21
Q

Pros and cons of asexual reproduction

A

Pros:
Only 1 parent so time efficient
Quicker
Many offspring produced in favourable conditions

Cons:
Lack of variation

22
Q

Examples of organisms that can do both (a)sexual reproduction

A

Malaria
Fungi
Strawberries

23
Q

What chromosomes do males and females have

A

Males:
XY

Females:
XX

24
Q

What are alleles

A

Different versions of genes

Humans have 2 alleles of each gene, one from each parent

25
What is your phenotype
The result of your genotype - your physical appearance
26
What is cystic fibrosis
A recessive condition that causes the body to produce lots of stick mucus in air passages and pancreas For the child to have the disorder, both parents must carry the allele or have the disorder themselves
27
What is polydactyly
A dominant condition that causes the child to be born with extra fingers or toes The parent that carries the defective allele will also have the condition
28
How can embryos be screened for genetic disorders and pros and cons
Removing cells before IVF Also possible to get DNA from a child in the womb Pros: Can help stop suffering Treating disorders costs the Government a lot of money Cons: Prejudice Choosing desired characteristics Expensive
29
What did Mendel discover
Observed plants and discovered 'hereditary units' from each parent Discovered genes
30
What are characteristics influenced by
Genes and environment
31
What is Charles Darwin's theory of evolution
That only the fittest survive and that beneficial characteristics are passed on Nowadays we know that mutations occur during reproduction
32
What is speciation
When a new species is formed and cannot interbreed to produce fertile offspring any more
33
How does speciation occur
Environmental separation Adapt Change Grow apart Cannot interbreed
34
What is extinction and why does it happen
When no members of a species exist any more Can happen due to: Environment changes too quickly New predator New disease Catastrophic event
35
Reasons why people disagreed with Darwin
Went against religious beliefs Darwin couldn't fully explain how these characteristics came about Lack of other evidence
36
What did Lamarck believe
That if a characteristic was used a lot by an organism, it would be enhanced and then passed onto its offspring
37
What is selective breeding and pros and cons
Choosing which organisms to breed as they have desired characteristics Pros: Can get desired characteristics Cons: Reduces the gene pool which can lead to health problems
38
What is genetic engineering and pros and cons
Gene is cut using restriction enzymes and inserted into a vector Then introduced into the target organism Pros: Increase yield of food Can put nutrients into food Cons: Some people are against GM food May affect the number of wild flowers
39
What are the 2 ways plants can be cloned
Tissue culture - a few plant cells in growth medium and hormones Cuttings - snippets of the plant and then plant them (slower) but cheaper
40
What are the 2 ways you can clone animals
Embryo transplants - prize sperm and egg cells are taken artificially fertilised cloned embryos can be implanted into other animals Adult cell cloning - remove the nucleus from an egg cell and place the nucleus from an adult body cell into the egg cell electrically stimulated by shock and begins to divide then implanted into females
41
Pros and cons of cloning
Pros: Ideal offspring Could lead to other scientific discoveries around ageing Preserve endangered species Cons: Many clone humans in future Lack of variation
42
3 ways fossils are formed
Gradual replacement by minerals Casts and impressions Preservation in places where decay does not happen
43
Who was Wallace and what did he do
Speciation and warning colours in animals
44
What are the ways things are classified
Kingdom Phylum Class Order Family Genus Species
45
Who came up with the classification system
Carl Linnaeus

Biology AQA GCSE (7 decks)

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