Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GCSE Biology - Paper 1 > SB3 - Genetics > Flashcards

SB3 - Genetics Flashcards

You may prefer our related Brainscape-certified flashcards:
GCSE Religious Studies - Edexcel Route A flashcards GCSE Religious Studies - Eduqas Route A flashcards AP® Biology flashcards GCSE Geography - AQA flashcards Biology 101 flashcards GCSE Religious Studies - Edexcel Route B flashcards GCSE Religious Studies - Eduqas Route B flashcards
1
Q

What is sexual reproduction?

A

It is reproduction where genetic information from two organisms is combined to produce offspring that are genetically different to both parents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define the word ‘haploid’

A

Cells that have half the number of chromosomes of a normal cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define the word ‘diploid’

A

Cells that have two copies of each chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What word do we use for a fertilised egg?

A

Zygote

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What type of cell division creates egg and sperm cells?

A

Meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What type of cell division creates body cells?

A

Mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do cells have to do before they can undergo meiosis?

A

Replicate - make copies of their chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How many daughter cells are made during one cycle of meiosis?

A

Four

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How many daughter cells are made during mitosis?

A

Two

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How many times do cells divide in mitosis?

A

Once

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many times do cells divide in meiosis?

A

Twice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Cat sperm cells contains 19 chromosomes. How many chromosomes would you find in the cat’s skin cells?

A

38

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Horse liver cells contain 64 chromosomes. How many chromosomes are found in horse egg cells?

A

32

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Human muscle cells contain 46 chromosomes. How many chromosomes are found in a red blood cell?

A

None

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Spider plants reproduce using runners. Is this an example of sexual or asexual reproduction?

A

Asexual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What will need to happen before new shoots on the runners for them to become independent plants?

A

The shoots would need to develop a root system and produce enough leaves to maintain the shoots’ food supply by photosynthesis. To become fully independent of the parent plant the stem connecting the daughter plants to the parent must die and disappear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What name is given to the horizontal stem in this kind of propagation?

A

The horizontal stem is called a runner

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Name a commercially grown fruit whose plants are propagated in this way

A

The most familiar fruit propagated by runners is the strawberry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Before stem cuttings are planted, the cut end of the stem is often dipped in a hormone powder. What is the point of this?

A

The hormone powder contains a plant growth substance which promotes the formation of roots. It may also contain a fungicide which reduces the chance of fungus attack on the cut stem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

State two advantages of vegetative reproduction

A
  1. Reduces competition from other species
  2. Maintains desirable qualities in the offspring
  3. Good at colonising favourable areas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

State two advantages of sexual reproduction

A
  1. Produces greater variety in the offspring
  2. Good at colonising new areas
  3. Species more able to survive an epidemic
  4. Species more able to survive environmental change
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What name is given to the population of genetically identical offspring which result from a process of asexual (vegetative) reproduction?

A

A clone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is mitosis used for?

A

Making more body cells, growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is meiosis used for?

A

Making gametes (e.g. sperm and eggs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Where does meiosis happen?

A

Ovaries and testes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is a gamete?

A

A sex cell (e.g. sperm or egg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is differentiation?

A

When an unspecialised cell becomes specialised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How does differentiation vary in animal and plant cells?

A

Most plant cells are able to be differentiated throughout their lives. In animals, only embryonic stem cells are able to differentiate into any specialised cell. Adult stem cells can only differentiate into a small number of specialised cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How many pairs of chromosomes are there in a normal human body?

A

23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How many chromosomes in a human sperm cell?

A

23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How many chromosomes in a human egg cell?

A

23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Who was Mendel?

A

An Austrian monk who laid the foundations of genetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are the three conclusions Mendel made after completing his work on pea plants?

A
  1. Characteristics are determines by ‘hereditary units’
  2. Hereditary units are passed on, unchanged from both parents - one unit from each parent
  3. Hereditary units can be dominant or recessive. The dominant characteristic will always be expressed when present
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Why didn’t Mendel get any credit for his work while he was alive?

A

Nobody knew about genes, chromosomes or DNA when Mendel was alive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Explain how DNA testing can be used to identify the father of a child

A

DNA profile of both the baby and its mother must be known. Take a cell sample from the child and father. Isolate the DNA sample from each. Use enzymes to cut up each sample. Place samples in a gel and run a current through the gel. Compare the pattern of DNA fragments from each sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Give two examples of the advantages of genetic profiling

A

It is very reliable because no two people have the same DNA (except identical twins), used to determine paternity, used to identify genetic disorders early, used to place suspects at a crime scene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Give two examples of the disadvantages of genetic profiling

A

DNA data might be stolen and used by insurance / loan / employers, storage of DNW profiles could be seen as an invasion of privacy. Theft of DNA profiles from a database, DNA can be planted at a crime scene causing miscarriages of justice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Name the monomers of DNA

A

Nucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Describe the general structure of a molecule of nucleotide

A

A sugar group, a phosphate group and a base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Name the four bases found in DNA

A

A - adenine, T- thymine, C - cytosine, G - guanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Which molecules make up the ‘backbone’ of the DNA strand?

A

The sugar and phosphate bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Describe the complementary pairing found in DNA molecules

A

Adenine only links to Thymine whilst Cytosine only links to Guanine (A - T, C - G)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What type of bonding occurs between the complementary pairs of DNA?

A

Hydrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Describe how to extract DNA from a banana (4 marks)

A
  1. Mash up some banana and mix it into a beaker containing washing up liquid and salt
  2. Filter the mixture
  3. Slowly put some ice-cold ethanol to the filtrate
  4. The DNA will start to precipitate into long white strands which should be removed using a glass rod
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What does the washing up liquid do to the banana?

A

Break down cell membranes to release the DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the role of the salt in DNA extraction?

A

Makes the DNA molecules stick together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Why is cold ethanol used?

A

DNA is not soluble in cold ethanol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What should you see when the cold ethanol is added to the filtrate solution?

A

White strands of DNA should become visible as they precipitate out of the solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What risk does the ethanol pose?

A

It is flammable so could catch light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

How is the risk from ethanol reduced?

A

Keep lit flames away from the ethanol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What term is used to describe a section of DNA that codes for a specific protein?

A

A gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What term is used to describe all of an organism’s DNA?

A

Its genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What does the DNA control the production of in cells?

A

Protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What are proteins made of?

A

Long chains of amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Explain why each protein has a specific shape

A

The amino acid chains fold up to give the protein of its shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What decides the order of amino acids in a protein?

A

The order of bases on DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

How many bases make a code for an amino acid?

A

Three

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What do we call the bases that make up a gene?

A

Base triplet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Some sections of DNA are non-coding. What does this mean?

A

The DNA does not code for any amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What is a mutation?

A

A rare, random change of an organism’s DNA base sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

If a mutation happens in a coding region of DNA, what is produced?

A

A different version of the gene - a variant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What can non-coding sections of DNA do to genes?

A

Switch them off and on

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is the first stage of protein synthesis?

A

Transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Where in the cell does the first stage of protein synthesis occur?

A

The nucleus

65
Q

Name the second stage of protein synthesis

A

Translation

66
Q

Where in the cell does the second stage of protein synthesis occur?

A

The cytoplasm

67
Q

Which sub-cellular structures are involved in the second stage of protein synthesis?

A

Ribosomes

68
Q

Name the molecule that is needed to make a copy of the DNA bases sequence of a gene

A

Messenger RNA (mRNA)

69
Q

How is messenger RNA (mRNA) similar to DNA?

A

It is a polymer of nucleotides

70
Q

How is the messenger RNA (mRNA) different to DNA?

A

It uses Uracil (U) instead of Thymine (T). It is shorter and only a single strand

71
Q

Name the enzyme that is needed to make mRNA

A

RNA polymerase

72
Q

What is the first thing that the RNA polymerase does to start the process of making mRNA?

A

The RNA polymerase binds to a region of non-coding DNA in front of a gene

73
Q

Describe what happens next as the two strands of DNA unzip

A

The RNA polymerase moves along on the strands of DNA, using the code as a template to make mRNA

74
Q

What ensures that the mRNA is complementary to the gene?

A

The base pairing between the DNA and RNA

75
Q

What happens to the mRNA once it is made?

A

It moves out of the nucleus and binds to a ribosome in the cytoplasm

76
Q

Name the molecules that bring amino acids to the ribosomes

A

Transfer RNA (tRNA)

77
Q

What are the base triplets in mRNA known as?

A

Codons

78
Q

Name the part of the tRNA that is complementary to the codon for the amino acid

A

Anticodon

79
Q

How is the order of amino acids brought to the ribosomes controlled?

A

By the pairing of the codon and anticodon

80
Q

What does the ribosome do to the amino acids?

A

Joins them together

81
Q

What is a polypeptide?

A

A chain of amino acids (another word for a protein)

82
Q

How do variants in the non-coding DNA at the start of a gene affect an organism’s phenotype?

A

It affects how well RNA polymerase binds to the DNA

83
Q

A sample of DNA is analysed and 46% of the base pairs contain thymine (T). If there are 2.16 x 10^6 base pairs in the sample, how many base pairs contain cytosine (C)?

A

1.17 x 10^6 (1166400)

84
Q

What are alleles?

A

Different versions of a gene

85
Q

How many alleles of a gene do nerve cells contain?

A

Two

86
Q

How many alleles of a gene do egg cells contain?

A

One

87
Q

Define heterozygous

A

When an organism has two different alleles for a specific gene

88
Q

Define homozygous

A

When an organism has two alleles that are the same for a specific gene

89
Q

What type of allele always controls a characteristic?

A

Dominant

90
Q

What type of allele needs to have two copies for it to be shown?

A

Recessive

91
Q

Define the term ‘genotype’

A

The alleles that make up an organism’s genome

92
Q

Define the term ‘phenotype’

A

The physical characteristics that are controlled by alleles

93
Q

What are the sex chromosomes for a male?

A

XY

94
Q

What are the sex chromosomes for a female?

A

XX

95
Q

Define the term ‘monohybrid inheritance’

A

A characteristic that is controlled by a single gene

96
Q

How is monohybrid inheritance studied?

A

Using monohybrid crosses - crossing (breeding) two parents to look at just one characteristic

97
Q

Define the term ‘carrier’

A

A person who has one copy of a faulty allele that causes a disorder but doesn’t have any symptoms

98
Q

What is the chance of a child having a disorder if both parents are carriers?

A

1 in 4 chance - 25%

99
Q

What is the chance of a child being a carrier if both parents are carriers?

A

1 in 2 chance / 2 in 4 chance - 50%

100
Q

What can genetic diagrams, like the Punnet square, be used for?

A

To predict and explain the outcomes of monohybrid crosses

101
Q

In genetics, what does a family pedigree show?

A

How a characteristic or disorder is inherited in a group of related people

102
Q

Why will you only inherit cystic fibrosis if you get the cystic fibrosis allele from both parents?

A

Cystic fibrosis is controlled by a recessive allele so two copies are needed for the characteristic to be displayed

103
Q

Why can one parent of polydactyl pass the condition on?

A

Polydactyl is controlled by a dominant allele

104
Q

Why are carriers of cystic fibrosis not affected by the disorder?

A

The cystic fibrosis allele is recessive. Carriers have one normal copy of the allele as well as one cystic fibrosis allele. The normal copy is dominant so it controls the phenotype

105
Q

A couple have a baby with cystic fibrosis yet neither parent has the condition. Draw a diagram to show how this happened and give the probability of this happening again

A

25% risk

106
Q

A plant with red flowers is crossed with a white-flowered plant of the same species. All the seeds, when grown, produce plants with red flowers. Assuming that the flower colour is controlled by a single pair of alleles, which allele is dominant and which is recessive?

A

The allele for red-coloured flowers must be dominant if no white flowers appear in the first generation (assuming a very large sample)

107
Q

If a dominant allele for tall plants is represented by the letter D, what letter should represent the corresponding recessive allele?

A

The recessive allele is d

108
Q

In cats, the allele (S) for short fur is dominant to the allele (s) for long fur. What is the genotype of a true-breeding, long-furred cat?

A

A true-breeding, long-furred cat has the genotype ss

109
Q

In cats, the allele (S) for short fur is dominant to the allele (s) for long fur. What is the phenotype of a cat with genotype Ss?

A

The Ss genotype will produce a short-furred phenotype

110
Q

In cats, the allele (S) for short fur is dominant to the allele (s) fro long fur. In the Ss genotype, which allele is expressed in the phenotype?

A

In the Ss genotype, the dominant allele (S) will be expressed

111
Q

Which of the following genotypes is (i) heterozygous: SS, Ss, ss?

A

Ss

112
Q

Which of the following genotypes is (I) homozygous dominant: SS, Ss, ss?

A

SS

113
Q

In rabbits the dominant allele (B) produces black fur. The allele (b) for white fur is recessive. What colour fur will a rabbit with BB alleles have?

A

Black

114
Q

In rabbits the dominant allele (B) produces black fur. The allele (b) for white fur is recessive. What colour fur will a rabbit with Bb alleles have?

A

Black

115
Q

In rabbits the dominant allele (B) produces black fur. The allele (b) for white fur is recessive. What colour fur will a rabbit with bb alleles have?

A

White

116
Q

In rabbits the dominant allele (B) produces black fur. The allele (b) for white fur is recessive. What colour fur will a rabbit with bB alleles have?

A

Black

117
Q

Which rabbits are homozygous for coat colour: BB, Bb, bB, bb?

A

BB, bb

118
Q

If rabbits BB and bb were mated together and had 12 babies, how many of these would you expect to be black?

A

All 12 - they all have one dominant allele

119
Q

If rabbits Bb and bB were mated together and had 48 babies, how many of these would you expect to be white?

A

Ratio of 3 black to 1 white baby, which is 36 black and 12 white

120
Q

If rabbits Bb and bb were mated together on several occasions and had a total of 50 babies, how many of these would you expect to be black?

A

50% black and 50% white, (i.e. 25 of each)

121
Q

The alleles controlling the ABO blood groups are given the letters IA (group A), IB (group B) and i (group O). What alleles could be found on the chromosomes for a person with Type A blood?

A

IA, IA or IA, i

122
Q

What alleles could be found on the chromosomes for a person with Type B blood?

A

IB, IB or IB, i

123
Q

What alleles could be found on the chromosomes for a person with Type O blood?

A

IA, IB

124
Q

What alleles could be found on the chromosomes for a person with Type AB blood?

A

i, i

125
Q

Give three examples of human disorders which are caused by the action of a single pair of alleles. In each case say whether the harmful allele is dominant or recessive to the non-harmful allele

A

Any three from haemophilia (recessive), albinism (recessive), phenylketonuria (recessive), red-green colour blindness (recessive), sickle-cell anaemia (partially recessive), polydactyl (recessive)

126
Q

What is the genotype for human males?

A

XY

127
Q

What is the genotype for human females?

A

XX

128
Q

In humans, is it the sperm or the ovum which determines the sex of the offspring?

A

The sperm determines the sex of the offspring

129
Q

Give a reason for why the sperm determines the sex of the offspring

A

All the ova contain an X chromosome. Half the screens carry an X chromosome and half carry a Y chromosome

130
Q

When a particular gene is said to be ‘sex-linked’, on which chromosome is that gene usually present?

A

A sex-linked gene is usually carried on the X chromosome and is absent from the Y chromosome

131
Q

One form of colour-blindness is a sex-linked inherited condition controlled by a recessive allele. Use the symbols X and Y for the sex chromosomes and N and n for the alleles for normal or defective colour vision to show the genotype of a normal male

A

XN, Y

132
Q

Show the genotype of a colour-blind female

A

Xn Xn

133
Q

Show the genotype of a colour-blind male

A

Xn Y

134
Q

Show the genotype of a normal (carrier) female

A

XN Xn

135
Q

Show the genotype of a normal (non-carrier) female

A

XN XN

136
Q

What is the chance of a carrier female and non-colour-blind male having a colour-blind child?

A

25% / 1 in 4

137
Q

What is the chance of a carrier female and non-colour-blind male having a colour-blind son?

A

25% / 1 in 4

138
Q

How do we classify blood types?

A

ABO blood group system

139
Q

Explain why ABO blood groups show codominance

A

Both alleles present affect the phenotype

140
Q

What are the possible genotypes of a person with Type AB blood?

A

AB

141
Q

What are the possible genotypes of a person with Type O blood?

A

OO

142
Q

What are the possible genotypes of a person with Type A blood?

A

AO / OA

143
Q

What are the possible genotypes of a person with Type B blood?

A

BO / OB

144
Q

What do we call disorders that show a different pattern of inheritance in women and men?

A

Sex-linked genetic disorders

145
Q

Explain why men are more likely to have red-green colour blindness compared to women

A

Need to have not of red-green colour genes because it is recessive. It is found on the X chromosome. Men only have one X chromosome and therefore if they have the recessive allele they will definitely be colour-blind. However, women have two X chromosomes and therefore have to have two copies to have the disorder

146
Q

Use a Punnett square to calculate the probability of having a boy or a girl who is colour blind if the father is NOT colour blind and the mother is a carrier of the allele

A

Boy - 50% / Girl - 0%

147
Q

Using a Punnett square explain why a mother who is blood group A and a father with blood group B could have children who are any of the four blood groups

A

Mum - AO, Dad - BO, Offspring AB - 25%, A - 25%, B - 25%, O - 25%

148
Q

What type of variation is caused by different alleles?

A

Genetic variation

149
Q

What type of variation is caused by interacting with your surroundings?

A

Environmental variation

150
Q

Explain what type of variation controls the length of hair

A

Environmental - you can cut your hair

151
Q

Explain what type of variation controls blood group

A

Genetic

152
Q

Explain what type of variation controls height

A

Genetic and Environmental - genes control the possible growth, the amount of nutrition can also stunt growth

153
Q

What type of chart would you use to show variation in leaf length?

A

Frequency chart

154
Q

What type of chart would you use to show variation in the numbers of leaves on a plant?

A

Bar chart

155
Q

What type of chart would you use to show the growth of a plant over a month?

A

Line graph

156
Q

What shape of graph is made by continuous variation?

A

Bell chart

157
Q

What type of distribution is shown by the shape of graph that is made by continuous variation?

A

Normal distribution

158
Q

Where is the most common value on a continuous variation graph?

A

The middle

159
Q

What happens to the number of individuals as the values move away from the median?

A

There are fewer individuals

GCSE Biology - Paper 1 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions