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Biology GCSE > Inheritance > Flashcards

Inheritance Flashcards

1
Q

Which of these statements is true
Genes make up chromosomes.
Chromosomes make up genes.

A

Genes make up chromosomes

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2
Q

Different genes control the development of different _______________

A

Characteristics

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3
Q

What is a gene

A

A section of DNA which codes for 1 characteristic

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4
Q

Describe the structure of a DNA molecule

A

Double helix

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5
Q

How can you work out the sequence if the bases on one strand by looking at the sequence on the other

A

It is always the opposite

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6
Q

‘A’ goes with ___

And ‘C’ goes with ___

A

A –> T

C –> G

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7
Q

___ bases code for one amino acid

A

3

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8
Q

What is a mutation

A

A random change in the DNA

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9
Q

What is the genotype

A

Your complete genetic identity… the allele pair (You may be {B b} or {B B}

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10
Q

What is the phenotype

A

The observable characteristics (Brown eyes)

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11
Q

Inside every cell in our bodies there is ___________ information. The information is carried in __________

A

Genetic information

Genes

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12
Q

Some characteristics are not present due to genes but by the ______________

A

Environment

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13
Q

Some genes can be controlled by both genes and the environment e.g…

A

For example height and weight

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14
Q

List 2 examples of continuous variation in humans

A

Height

Weight

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15
Q

List 3 types of discontinuous variation in humans

A

Eye colour
Hair colour
Blood type

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16
Q

List 3 causes of variation

A

Genes
Environment
Mutation

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17
Q

What are the 4 stages in mitosis in order

A

Prophase
Metaphase
Anaphase
Telophase

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18
Q

Describe the main stages in the division of cell?

A

The dividing cell copies each chromosome before it divides. Therefore every cell has one copy of every chromosome. 2 chromatids make up each chromosome. These attach to a structure called a spindle. The spindles then shorten and pull the chromatids of each chromosome to the polar ends. 2 new nuclei form, both with a copy of each chromosome

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19
Q

Why does the chromosome need to make an EXACT copy of itself before the cell can divide

A

Otherwise both cells will not receive all the genes

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20
Q

When a cell is about to divide, it first makes an exact copy of each DNA molecule - this is called ______________

A

Replication

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21
Q

How does a mutation occur

A

During replication, if a mistake is made.

22
Q

Name the 4 ways a mutation can occur

A

Duplication
Deletion
Substitution
Inversion

23
Q

Some _____________ occur in body cells and will only affect that particular cell. If the ___________ is not lethal and the cell containing the mutation divides, then a group of cells will have that ___________. When the organism dies, the ___________ is ______. Only a __________ in the __________ can be passed on to the next generation

A 
Mutations
Mutation
Mutation
Mutation
Lost
Mutation
Gametes
24
Q

What are the 4 effects of mutations

A

Lethal
Harmful
Silent
Beneficial

25
Q

New alleles originate by __________

A

Mutation

26
Q

Only mutations in ________ can be inherited

A

Gametes

27
Q

New alleles introduce genetic ____________

A

Variation

28
Q

Causes of gene mutation

A 
Ionising radiation
Viruses and microorganisms
Environmental poisons
Tobacco
Alcohol and diet
29
Q

What is an allele

A

A different version of a gene

30
Q

What does homozygous mean

A

The same alleles

31
Q

What does heterozygous mean

A

Different alleles

32
Q

Is it possible for a recessive allele to be passed on

A

Yes… both alleles must be present for that characteritic to be shown

33
Q

What is codominance

A

When the characteristics are mixed. The genotype is heterozygous. Neither allele is dominant or recessive to the other one. You get a mix of the 2 characteristics.

34
Q

Male genotype

A

XY

35
Q

Female genotype

A

XX

36
Q

DNA replication. The DNA must first ___________. An ___________ called helicase helps. Each strand acts a template. The DNA ________________ match up to the bases on each strand. C matches with ____ and A matches with ___. Another enzyme, DNA polymerase, joins the ________________ together along the new strand. Another enzyme, ligase, helps stick them together

A 
Unwind
Enzyme
Nucleotides
G
T
Nucleotides
37
Q

Chromosomes are located in a __________ which is surrounded by ______________

A

Nucleus

Cytoplasm

38
Q

Each ___________ consists of a row of genes

A

Chromosome

39
Q

Differences between organisms of the same species are known as ______________

A

Variation

40
Q

Body cells contain 46 chromosomes. Gametes contain half this number and are therefore said to be ___________

A

Haploid

41
Q

Number of chromsomes: Ovum

A

23

42
Q

Number of chromsomes: Sperm

A

23

43
Q

Number of chromsomes: Zygote

A

46

44
Q

Explain how mitosis results in cells with identical sets of genetic information

A

Because before the cells divide the DNA replicates itself. The chromosome then splits in 2 before the cell splits sp both cells have an identicle chromosome

45
Q

First the DNA ___________
Then, the DNA copies itself before it coils up and forms _______________
The _______________ then line up in the centre of the cell
Next, the arms of each ________________ are pulled apart
New _____________ form around the cell nuclei
The cell divides.
This process is known as ___________.

A 
Uncoils
Chromosomes
Chromosomes
Chromosome
Membranes
Mitosis
46
Q

Why do gametes have half the usual number of chromosomes

A

For variation, when fertilisation occurs it goes back to the usual number

47
Q

How does gamete formation lead to genetic variation

A

The child isn’t identical to one parent. It’s a mix of both.

48
Q

New forms of genes arise from changes known as ___________________ in the existing genes. These occur naturally and are important for producing ______________

A

Mutations

Variation

49
Q

Name something which increases the chance of a mutation occuring

A

Exposure to ionising radiation

Exposure to chemicals known as mutagenes

50
Q

What has to happen for a mutation to be passed on

A

The mutation has to occur in the sex cells

Biology GCSE (28 decks)

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