Brainscape's Knowledge GenomeTM

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


See full index

Biology GCSE AQA > 6. Cell Division & DNA > Flashcards

6. Cell Division & DNA Flashcards

1
Q

Why does mitosis take place?

A
  • growth

* replace damaged cells

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

What has to happen before mitosis?

A

The chromosomes replicate

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

How many divisions are there in mitosis?

A

1

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

Are the cells haploid or diploid in mitosis?

A

Diploid (in mammals)

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

How many new cells are produced in mitosis?

A

2

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

Are the new cells identical or different in mitosis?

A

Identical

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

What does diploid mean?

A

Has a full set of chromosomes

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

What does haploid mean?

A

Half the number or chromosomes

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

What can meiosis also be referred to as?

A

Reduction division

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

Where does meiosis only happen?

A

In the cells of the reproductive organs

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

What does meiosis produce?

A

Gametes

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

Where are gametes produced in animals?

A

Ovaries and testes

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

Where are gametes produced in plants?

A

Ovule and anther

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

How many chromosomes do the gametes produced in meiosis have?

A

Half the number of the parent cell (humans - 23 chromosomes instead of 23 pairs of chromosomes)

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

How many copies of each chromosome do gametes have? Why?

A

One so when they fuse the zygote has the normal amount of chromosomes

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

Are gametes diploid or haploid?

A

Haploid

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

Are zygotes diploid or haploid?

A

Diploid

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

What happens to the zygote formed at fertilisation?

A

Divides by mitosis to produce more cells that differentiate as embryo develops

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

How does meiosis turn one cell into four new cells in humans?

A
  • diploid cell in ovaries or testes (46 chromosomes)
  • chromosomes replicate (still 46 chromosomes)
  • pairs of chromosomes line up at equator, thicken and spindles attach
  • chromosome pairs separate into two new cells and a nucleus reforms
  • spindles attach to the (2) duplicates of chromosomes and duplicates are pulled apart into separate cells
  • four new cells have formed (23 chromosomes)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does meiosis turn one cell into four new cells in general?

A
  • diploid cell
  • chromosomes replicate
  • pairs of chromosomes line up at equator, thicken and spindles attach
  • chromosome pairs separate into two new cells and a nucleus reforms
  • spindles attach to the (2) duplicates of chromosomes and duplicates are pulled apart into separate cells
  • four new cells have formed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How many chromosomes are in a human cell produced by mitosis?

A

46

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How many chromosomes are in a human cell produced by meiosis?

A

23

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

What are the two gametes produced by humans?

A

egg and sperm

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

How do mitosis and meiosis differ in terms of the number of daughter cells produced?

A

Mitosis produces two daughter cells whereas meiosis produces four daughter cells

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

How do mitosis and meiosis differ in terms of the number of cell divisions that occur?

A

In mitosis one cell division occurs whereas in meiosis two occur

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

How do mitosis and meiosis differ in terms of the nature of the cells they produce?

A

Mitosis produces genetically identical cells whereas meiosis produces cells that are all genetically different

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

How do mitosis and meiosis differ in terms of when it occurs?

A

Mitosis occurs during growth and asexual production whereas meiosis occurs during sexual reproduction

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

How do mitosis and meiosis differ in terms of the number of chromosomes that are passed on to their daughter cells?

A

In mitosis one copy of each chromosome goes to each of the new daughter cells, whereas in meiosis only half of the chromosomes go to each of the new daughter cells

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

How do mitosis and meiosis differ in terms of what other names they can be called by?

A

Mitosis is otherwise known as copying division whereas meiosis is otherwise known as reduction division

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

Why is important that the four daughter cells produced in meiosis contain half the number of chromosomes?

A
  • to restore the original chromosome number when they get fertilised
  • to prevent the doubling of the chromosome number
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the difference between mitosis and meiosis?

A
  • in mitosis two daughter cells are produced; in meiosis four are produced
  • in mitosis there is one cell division; in meiosis there are two
  • mitosis produces genetically identical cells; meiosis does not
  • mitosis occurs during asexual production; meiosis occurs during sexual production
  • in mitosis one copy of each chromosome goes to each of the new daughter cells; in meiosis only half of the chromosomes go to each of the daughter cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How do asexual and sexual reproduction differ in terms of how many parents are involved?

A

Asexual needs one parent whereas sexual involves the mixing of genetic information from two organisms

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

How do asexual and sexual reproduction differ in terms of fertilisation?

A

In asexual there is no fusion of gametes wheres in sexual gametes fuse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How do asexual and sexual reproduction differ in terms of their offspring?

A

In asexual offspring are genetically identical to that parent whereas in sexual offspring are genetically different from either parent

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

How do asexual and sexual reproduction differ in terms of genetic variation?

A

In asexual variation is caused by random mutations whereas in sexual offspring are genetically different from their parents

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

How many daughter cells are produced in mitosis?

A

2

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

How many daughter cells are produced in meiosis?

A

4

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

How many cell divisions occur in mitosis?

A

1

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

How many cell divisions occur in meiosis?

A

2

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

When does mitosis occur?

A

During growth and asexual reproduction

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

When does meiosis occur?

A

In the formation of gametes during sexual reproduction

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

What can mitosis also be referred to as?

A

Copying division

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

What can meiosis also be referred to as?

A

Reduction division

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

How many parents are involved in asexual reproduction?

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

How many parents are involved in sexual reproduction?

A

2

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

What process allows asexual reproduction to occur?

A

Mitosis

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

How is genetic variation caused during asexual reproduction?

A

Random mutations

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

Examples of asexual reproduction?

A
  • strawberry runners
  • potato runners
  • starfish
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What are the female gametes in animals?

A

Egg cells (ova)

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

What are the male gametes in animals?

A

Sperm

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

Where are female gametes produced in animals?

A

Ovaries

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

Where are male gametes produced in animals?

A

Testes

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

What are the female gametes in plants?

A

Egg cell nucleus

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

What are the male gametes in plants?

A

Pollen grain nucleus

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

Where are the female gametes produced in plants?

A

Ovary of carpel

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

Where are the male gametes produced in plants?

A

Anther of stamen

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

What is the form of asexual reproduction in bacteria?

A

Binary fission

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

Advantages of sexual reproduction?

A

Variation in the offspring increases the chances of survival if circumstances change

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

Why does genetic variation increase chance of survival?

A

If circumstances change some individuals will survive the chance due to having different characteristics

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

Disadvantages of sexual reproduction?

A
  • slow

* finding a mate takes time and energy

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

Advantages of asexual reproduction?

A
  • only needs to be one parent so no energy or time is wasted finding a mate
  • large numbers of clones are produced when conditions are favourable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Disadvantages of asexual reproduction?

A

Vulnerable to extinction due to lack of variation - could easily catch disease

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

Which organisms can reproduce sexually and asexually depending on their circumstances?

A
  • mosquitoes (malaria)
  • fungus (releasing spores)
  • plants that produce seeds sexually but reproduce sexually
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

How does malaria reproduce sexually and asexually?

A

The parasite reproduces sexually when it’s in the mosquito and asexually when it’s in the human host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

How does fungus reproduce sexually and asexually?

A
  • asexually-produced spores form fungi that are genetically identical to the parent fungus
  • sexually-produced spores introduce variation and are often produced in response to a change in the environment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

How do plant species reproduce sexually and asexually?

A
  • produce their seeds sexually

* reproduce asexually e.g. daffodil bulbs - new bulbs divide off main bulb but each bulb grows into new identical plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Where does the asexual reproduction of malaria take place?

A

In the human liver and red blood cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Where does sexual reproduction of malaria take place?

A

In the mosquito, triggered by the lower body temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

How does sexual reproduction of malaria occur?

A
  • in mosquitoes, triggered by lower body temperature
  • in 20 minutes the sexual forms develop and burst out of the RBCs and fuse to form a zygote
  • meiosis then occurs to form new asexual parasites
  • these go to infect human hosts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What chemical are chromosomes made of?

A

DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What is genetic information carried on?

A

Chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

What is a section of DNA called?

A

A gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What does DNA stand for?

A

Deoxyribonucleic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

What is all the genetic material in a cell composed of?

A

DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What is DNA?

A

A polymer of nucleotides, made up of two stands forming a double helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Where is DNA found in?

A

Chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What does a nucleotide consist of?

A

A common sugar and phosphate group with one of 4 different bases attached to the sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What are the four bases that DNA contains?

A

A, T, C and G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

How many bases is the code for an amino acid?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What does three bases code for?

A

An amino acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

What does the order of bases control?

A

The order in which amino acids are assembled to produce a protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Where are the genes controlling a certain characteristic located on a pair of chromosomes?

A

They are in the same location on each chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

What is the shape of a DNA molecule?

A

A double helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

What is a nucleotide?

A

A monomer which makes up DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

What is complimentary base pairing?

A

When each base in a DNA strand links to a base on the opposite strand in the helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

What does A pair with?

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What does T pair with?

A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What does G pair with?

A

C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What does C pair with?

A

G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

What does each gene code for?

A

A particular sequence of amino acids which are put together to make proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

How many amino acids are there?

A

20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

How are proteins made?

A

Amino acids are put together in many different orders

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

How long is a gene?

A

Hundred or thousands of bases long

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

What is the genome of an organism?

A

The entire genetic material of that organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

Why does A and always pair with T and C with G?

A
  • bonds won’t form in the correct way

* physical size - bases are different lengths so there could be a bulge on the DNA if bases too long

96
Q

What has the study of the human genome allowed for?

A
  • the search for genes being linked to different types of disease
  • the understanding and treatment of inherited disorders
  • tracing human migration patterns from the past
97
Q

How does protein synthesis occur?

A
  • the code from DNA is copied to form a messenger molecule
  • this leaves the nucleus and moves to a ribosome
  • carrier molecules bring the code for specific amino acids to the ribosome and attach to the messenger molecules in the order determined by the sequence of bases
  • the amino acids are joined together in the correct order to form the protein
98
Q

What happens after a chain of amino acids has been assembled during protein synthesis?

A

It folds into a unique shape which allows the protein to perform its task

99
Q

What allows a protein to do its job?

A

It’s structure

100
Q

Examples of proteins?

A
  • hair protein (keratin)
  • hormones
  • collagen
  • enzymes
101
Q

Who discovered the structure of DNA?

A

Rosalind Franklin

102
Q

What is a mutation?

A

A random change in an organism’s DNA

103
Q

When do mutations occur?

A

All the time

104
Q

What is often the cause of mutations?

A

A mistake in the copying of DNA before a cell divides

105
Q

What arise due to mutation?

A

New forms of genes

106
Q

How can the chance of mutation be increased?

A

Exposure to some chemicals and radiation

107
Q

How can a mutation change the protein synthesised from that gene?

A
  • one of the amino acids may be substituted for another
  • this may change the intermolecular forces between the amino acids so the protein may change shape
  • it may lose function
108
Q

What do non-coding parts of DNA do?

A

Switch genes on and off

109
Q

What happens if there is a mutation to the non-coding areas of DNA?

A

It may affect how genes are expressed

110
Q

What are the different forms of a gene called?

A

Alleles

111
Q

How many alleles do gametes have?

A

1

112
Q

How many alleles do cells in an organism have, apart from gametes?

A

2 - 1 on each chromosome of a pair

113
Q

Why do we have two alleles in each cell?

A

We inherit half from our mother and half from our father

114
Q

What can an allele be?

A
  • dominant

* recessive

115
Q

What is a gamete?

A

A male or female sex cell

116
Q

What is a gene?

A

A length of DNA found on a chromosome that carries the instructions needed to make a protein

117
Q

What is a dominant allele?

A

An allele that is always expressed in the phenotype

118
Q

How is the dominant allele represented?

A

By a capital letter

119
Q

What does it mean when an organism is homozygous?

A

It has two alleles for a particular gene that are the same

120
Q

What is a genotype?

A

The alleles present for a particular gene in an organism (the letters)

121
Q

What is a chromosome?

A

A thread-like structure in the cell nucleus, made of a molecule of DNA, which carries genes

122
Q

What is an allele?

A

One of the different forms of a particular gene

123
Q

What is a recessive allele?

A

An allele that is only expressed in the phenotype if two copies are present

124
Q

How is the recessive allele represented?

A

a lowercase letter

125
Q

What does it mean when an organism is heterozygous?

A

It has two alleles for a particular gene that are different

126
Q

What is a phenotype?

A

The characteristic that is shown or expressed

127
Q

What do genetic diagrams show?

A

How certain characteristics are inherited

128
Q

What did Gregor Mendel experiment on?

A

Peas

129
Q

What was the pattern regarding sample size and the Mendelian ratio?

A

The bigger the sample size of peas, the closer to the Mendelian ratio

130
Q

Were Mendel’s results reproducible?

A

Yes

131
Q

What type of allele is polydactyly caused by?

A

Dominant

132
Q

What type of allele is cystic fibrosis caused?

A

Recessive

133
Q

What is polydactyly?

A

Having extra fingers or toes

134
Q

What is cystic fibrosis?

A

A cell membrane disorder

135
Q

Will the parent with the defective polydactyly allele also have it? Why?

A

Yes because the allele is dominant

136
Q

What is the purpose of embryo screening?

A

To detect inherited genetic disorders in embryos

137
Q

What are the two types of embryo screening?

A
  • pre-implantation genetic diagnosis (PGD)

* chorionic villus sampling (CVS)

138
Q

What happens in pre-implantation genetic diagnosis?

A
  • during IVF, a cell is removed from the embryo and its genes analysed
  • only embryos with ‘healthy’ alleles are implanted into the uterus
  • embryos with ‘faulty’ alleles are destroyed
139
Q

What happens in chorionic villus sampling?

A
  • sample of cells taken from placenta at 10-13 weeks and genes analysed
  • if the embryo has an inherited disorder, the parents can decide whether or not to terminate the pregnancy
140
Q

Arguments for embryo screening?

A
  • helps to stop people suffering from inherited disorders
  • treating disorders costs government so could reduce healthcare costs
  • during IVF most embryos are destroyed anyway
  • if an inherited disorder is diagnosed through CVS, the parents don’t have to terminate the baby
141
Q

Arguments against embryo screening?

A
  • there may come a point where everyone wants to screen their babies to pick the most ‘desirable’
  • implies that people with genetic disorders are ‘undesirable’ - could create predjudice
  • after PGD rejected embryos are destroyed - unethical
  • risk that CVS could cause miscarriage
  • expensive
142
Q

How many pairs of chromosomes are in every human body cell?

A

23

143
Q

What do the 23rd pair of chromosomes control?

A

The sex of a person

144
Q

What sex chromosomes do males have?

A

X and Y, XY

145
Q

What does the Y chromosome cause?

A

Male characteristics

146
Q

What sex chromosomes do females have?

A

Two X chromosomes, XX

147
Q

What does the XX chromosome cause?

A

Female characteristics

148
Q

Which organisms did Mendel study?

A

Peas

149
Q

What type of peas did Mendel cross in the first generation?

A

Round peas and wrinkled peas (RR and rr)

150
Q

What type of peas did Mendel cross in the second generation?

A

Round peas and round peas

151
Q

What did Mendel call what we now know to be genes?

A

Hereditary units

152
Q

Why wasn’t Mendel’s theory first accepted by other scientists?

A

They didn’t know about genes, chromosomes or DNA

153
Q

What are species?

A

A group of organisms that are able to interbreed to produce fertile offspring

154
Q

What is variation?

A

The difference in the characteristics of individuals in a population

155
Q

What can variation be caused by?

A
  • genetic causes
  • environmental causes
  • a combination
156
Q

Where do variants in a population arise from?

A

Mutations

157
Q

How often do mutations occur?

A

All the time however very rarely will it lead to a new phenotype

158
Q

What happens if a new phenotype is suited to an environmental change?

A

It can lead to a relatively rapid change in species

159
Q

What is evolution?

A

A change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species

160
Q

What does the theory of evolution by natural selection state?

A

All species have evolved from simple life forms that first developed more than three billion years ago

161
Q

What happens if two populations of one species become so different in phenotype?

A

They can no longer interbreed to produce fertile offspring and have formed two new species

162
Q

When do two populations of one species become two different species?

A

When they become so different in phenotype that they can no longer interbreed to produce fertile offspring

163
Q

When does extinction occur?

A

When there are no remaining individuals of a species alive

164
Q

What are the causes of extinction?

A
  • environmental changes
  • new predator
  • new disease
  • competition
165
Q

What is the order of the general outline you need to use in a natural selection exam question?

A
  • variation
  • caused by mutation
  • which variation has an advantage and why
  • survive and breed
  • pass on advantageous genes to next generation
166
Q

What was Lamarck’s theory of evolution?

A
  • evolution of animals was caused by the inheritance of acquired characteristics
  • based on the idea that changes occur in an organism throughout it’s lifetime
167
Q

What was Darwin’s theory of evolution?

A
  • individual organisms within a species show a wide range of variation for a characteristic
  • individuals with characteristics most suited to the environment are more likely to survive
  • characteristics that have enabled these individuals to survive are passed on
168
Q

Why was the theory of evolution by natural selection only gradually accepted?

A
  • the theory challenged the idea that God made life
  • insufficient evidence to convince many scientists
  • mechanism of inheritance was not known until 50 years after the theory was published
169
Q

What does Darwin’s theory not include?

A

Ideas of genes/DNA

170
Q

Why do people have different ideas about how life began on earth?

A
  • religion
  • evidence - some theories have more than others
  • status of scientist
  • culture
171
Q

What are the conflicting theories of how life began on earth?

A
  • Darwin’s theory of natural selection
  • Lamarck’s theory of acquired characteristics
  • creationism
  • theory of intelligent design
172
Q

Why are there conflicting theories about how life on earth began?

A

Lack of evidence

173
Q

How do fossils produce evidence that species today have evolved from simpler organisms?

A
  • they are remains of organisms that lived a long time ago
  • they show changes over time
  • they have similar feature to present day species
174
Q

What are fossils?

A

The remains of organisms from many years ago

175
Q

How can fossils be formed?

A
  • from parts of organisms that have not decayed because one or more of the conditions needed to decay are absent
  • when parts of an organism are replaced by other materials as they decay
  • as preserved traces of organisms, such as footprints
176
Q

Example of fossils forming due to one or more of the conditions needed for decay being absent?

A

Insects in amber lacking oxygen for decay

177
Q

What does early forms of life being soft-bodied mean for our understanding?

A

They have few traces behind

178
Q

What are some sources of evidence for evolution?

A
  • fossils

* antibiotic resistance

179
Q

How does antibiotic resistance provide evidence for evolution?

A
  • bacteria evolve rapidly as they reproduce at a fast rate
  • bacteria can develop antibiotic resistance in a process of natural selection
  • mutations of bacterial pathogens produce new antibiotic resistant strains and the pathogens of the non-resistant strain are killed
  • population of resistant strain increases and spread
180
Q

Why do new species arise?

A
  • isolation - two populations of a species becoming separated
  • genetic variation
  • natural selection
  • speciation
181
Q

What is speciation?

A

When populations become so different that successful interbreeding is no longer possible

182
Q

What is selective breeding?

A

A process used by humans to produce different breeds of animals or varieties of plants

183
Q

How is selective breeding executed?

A
  • choosing parents with the desired characteristics from a mixed population
  • breeding these together
  • from the offspring, breed those with the desired characteristics
184
Q

Some examples of how selective breeding can be useful?

A
  • disease resistance in crops
  • animals which produce more meat/milk
  • domestic dogs with a gentle nature
  • large or unusual flowers
185
Q

What is inbreeding?

A
  • when future generations of selectively bred organisms share very similar genes
  • some diseases will be more dangerous as all the organisms would be affected
  • also there is increased risk of genetic diseases caused by recessive genes
  • also some genes would be lost, making more difficult to produce new varieties in the future
186
Q

What are some of the limitations of selective breeding?

A

Inbreeding:

  • more prone to disease
  • increased risk of genetic diseases
  • smaller gene pool
187
Q

What is genetic engineering?

A

A process which involves modifying the genome of an organism by introducing a gene from another organism

188
Q

What are the additional small pieces of genetic material in bacterial cells?

A

Plasmids

189
Q

What does the vector do in genetic engineering?

A

It is used to insert the gene into the required cells

190
Q

What is the vector usually during genetic engineering?

A

A bacterial plasmid or a virus

191
Q

Example of genetic engineering?

A

Gene for making human growth hormone inserted into sheep - so they will produce the hormone in their milk

192
Q

What are some current applications for plant genetic modification?

A
  • disease and pest resistant plants
  • keeping fruit and vegetables fresher for longer
  • plants that have increased nutritional benefits
  • producing soy with higher levels of anti-cancer proteins naturally found
193
Q

Advantages of genetic engineering?

A
  • treating diseases

* more efficient food production

194
Q

Disadvantages of genetic engineering?

A
  • long term effects e.g. changing genes could pass on problems to future generations
  • same with GM crops (changing genes may get into general circulation)
195
Q

Ethical issues of genetic engineering?

A
  • not a natural process and interfering with nature

* altering organisms for human gain seen to be against God’s will

196
Q

What is cloning?

A

When an identical copy of an organism is made

197
Q

What process is usually involved in cloning?

A

Mitosis (binary fission in bacteria)

198
Q

What are the four ways of cloning organisms?

A
  • cuttings
  • tissue culture
  • embryo transplants
  • adult cell cloning
199
Q

Advantages of using cuttings to clone plants?

A

They reproduce quickly and is quicker than tissue culture

200
Q

How is tissue culture used to clone plants? (process)

A
  • small tissue sample taken from parent plant and grown in agar with nutrients and hormones to form tissue
  • tiny identical plants are formed and then grown on
201
Q

What is an important condition that needs to be used when cloning cells using tissue culture?

A

The agar needs to be sterile so you don’t have bacteria contaminating it

202
Q

Advantages of using tissue culture to clone plants?

A
  • plants can be made very quickly
  • in very little space
  • all year round
203
Q

How are embryo transplants used to clone animals? (process)

A
  • each embryo is divided into individual cells and each cell grows into an embryo in the lab
  • embryos are transferred to host mothers
  • identical cloned calves are born
204
Q

In embryo transplants, what embryo is used initially?

A

From particular cattle e.g. a prized bull semen with a prized cow egg

205
Q

In embryo transplants, how does each cell grow into an embryo?

A

By mitosis

206
Q

In embryo transplants, who are the cloned organisms identical to?

A

Each other, but not the mothers that gave birth to them

207
Q

Advantages of embryo transplants to clone animals?

A

Produces hundreds of ideal offspring

208
Q

How is adult cell cloning used to clone animals? (process)

A
  • nucleus removed from unfertilised egg cell and nucleus from adult body cell is inserted into egg cell
  • electric shock stimulates egg cell to divide to form embryo
  • inserted into womb of an adult female
209
Q

Benefits of cloning?

A
  • lots of ideal offspring quickly produced with ideal characteristics
  • could help preserve endangered species
  • lead to a greater understanding of development of the embryo and age-related disorders
210
Q

Concerns of cloning?

A
  • cloned animals may not be as healthy as normal ones
  • reduced gene pool
  • may lead to cloning of humans
211
Q

What is the disadvantage if there is a reduced gene pool?

A

Fewer alleles available if there is an environmental change so if a new disease appeared, all might be wiped out

212
Q

What is classification?

A

When organisms are put into groups depending of their structure and characteristics

213
Q

What system did Carl Linnaeus develop?

A

The binomial system

214
Q

Who developed the binomial system?

A

Carl Linnaeus

215
Q

What did Linnaeus classify living things into?

A
  • kingdom
  • phylum
  • class
  • order
  • family
  • genus
  • species
216
Q

What is the mnemonic to remember the binomial system?

A

King prawn curry or fat greasy sausages

217
Q

What is the mnemonic to remember the binomial system? (and what they stand for!)

A
  • king - kingdom
  • prawn - phylum
  • curry - class
  • or - order
  • fat - family
  • greasy - genus
  • sausages - species
218
Q

What is the kingdom of humans?

A

Animalia

219
Q

What is the phylum of humans?

A

Chordata

220
Q

What is the class of humans?

A

Mammalia

221
Q

What is the order of humans?

A

Primale

222
Q

What is the family of humans?

A

Hominidae

223
Q

What is the genus of humans?

A

Homo

224
Q

What is the species of humans?

A

sapien

225
Q

What is the largest group in the binomial system?

A

Kingdom

226
Q

What is the newer model of classification?

A

The ‘three domain system’

227
Q

Who was the ‘three domain system’ developed by?

A

Carl Woese

228
Q

Why were new models of classification proposed?

A

Evidence of internal structures became more developed due to improvements in microscopes

229
Q

What are organisms divided into in the three domain system?

A
  • archaea
  • bacteria
  • eukaryota
230
Q

What are archaea?

A

Primitive bacteria usually living in extreme environments

231
Q

What do eukaryota include?

A

Protists, fungi, plants and animals

232
Q

What are the six kingdoms that organisms are classified into?

A
  • archaebacteria
  • eubacteria
  • protista
  • fungi
  • plantae
  • animalia
233
Q

What method is used to show how sciensts believe organisms are related?

A

Evolutionary trees

234
Q

What do evolutionary trees do?

A

Show how scientists believe organisms are related

235
Q

What do evolutionary trees use?

A

Current classification data for organisms and fossil data

236
Q

What is the importance of the binomial system for scientists around the world?

A

So all scientists use the same genus/species names so avoid confusion

Biology GCSE AQA (14 decks)

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