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Biology GCSE > Inheritance, Variation and Evolution > Flashcards

Inheritance, Variation and Evolution Flashcards

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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
Q

What is your phenotype

A

The result of your genotype - your physical appearance

26
Q

What is cystic fibrosis

A

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
Q

What is polydactyly

A

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
Q

How can embryos be screened for genetic disorders and pros and cons

A

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
Q

What did Mendel discover

A

Observed plants and discovered ‘hereditary units’ from each parent
Discovered genes

30
Q

What are characteristics influenced by

A

Genes and environment

31
Q

What is Charles Darwin’s theory of evolution

A

That only the fittest survive and that beneficial characteristics are passed on

Nowadays we know that mutations occur during reproduction

32
Q

What is speciation

A

When a new species is formed and cannot interbreed to produce fertile offspring any more

33
Q

How does speciation occur

A

Environmental separation
Adapt
Change
Grow apart
Cannot interbreed

34
Q

What is extinction and why does it happen

A

When no members of a species exist any more

Can happen due to:
Environment changes too quickly
New predator
New disease
Catastrophic event

35
Q

Reasons why people disagreed with Darwin

A

Went against religious beliefs

Darwin couldn’t fully explain how these characteristics came about

Lack of other evidence

36
Q

What did Lamarck believe

A

That if a characteristic was used a lot by an organism, it would be enhanced and then passed onto its offspring

37
Q

What is selective breeding and pros and cons

A

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
Q

What is genetic engineering and pros and cons

A

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
Q

What are the 2 ways plants can be cloned

A

Tissue culture - a few plant cells in growth medium and hormones

Cuttings - snippets of the plant and then plant them (slower) but cheaper

40
Q

What are the 2 ways you can clone animals

A

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
Q

Pros and cons of cloning

A

Pros:
Ideal offspring
Could lead to other scientific discoveries around ageing
Preserve endangered species

Cons:
Many clone humans in future
Lack of variation

42
Q

3 ways fossils are formed

A

Gradual replacement by minerals
Casts and impressions
Preservation in places where decay does not happen

43
Q

Who was Wallace and what did he do

A

Speciation and warning colours in animals

44
Q

What are the ways things are classified

A

Kingdom
Phylum
Class
Order
Family
Genus
Species

45
Q

Who came up with the classification system

A

Carl Linnaeus

Biology GCSE (7 decks)

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