Inheritance, variation and evolution Flashcards

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1
Q

What is a gamete?

A

A cell with half the number of chromosomes of the parent cell.

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2
Q

Name the male and female gametes in a) a human

b) a daisy plant

A

a) Male = sperm Female = egg

b) Male = pollen Female = egg

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3
Q

Name the shape which best describes the DNA polymer.

A

Double helix

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4
Q

How is DNA organised inside the cell nucleus?

A

Arranged in chromosomes

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5
Q

Which is larger, a chromosome or a gene?

A

Chromosome

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6
Q

What does a gene code for?

A

A particular sequence of amino acids

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7
Q

Write down the definition of the genome of a horse.

A

All the genetic material of the horse.

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8
Q

List two reasons why it is important to understand more about the human genome

A
  • To be able to identify the genes which are linked to different diseases
  • To understand and be able to treat inherited disorders
  • To use in tracing human migration patterns from the past.
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9
Q

What are three advantages of sexual reproduction?

A
  • Produce variation in the offspring
  • If environment changes can give a survival advantage meaning some organisms are likely to survive
  • Humans can speed up natural selection by selective breeding to increase food production
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10
Q

What are three advantages of asexual reproduction?

A
  • Only one parent needed
  • More time and energy-efficient as do not need to find a mate
  • Faster than sexual reproduction
  • Many identical offspring can be produced when conditions are favourable
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11
Q

List three organisms which reproduce using both sexual and asexual reproduction.

A
  • Malarial parasites
  • Fungi
  • Strawberry plants
  • Daffodils
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12
Q

Where would you find a nucleotide?

A

DNA

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13
Q

What does a nucleotide consist of?

A

Common sugar, phosphate group, base

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14
Q

What are the symbols of the 4 bases found in DNA?

A

A
T
C
G

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15
Q

What does the code for an amino acid consist of?

A

A sequence of three bases

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16
Q

Fill in the missing terms:
The long strands of DNA are made of alternating _____ and ______ sections.
Attached to each ________ is one of the four bases.
The DNA polymer is made up of repeating ____________ units.

A

Fill in the missing terms:
The long strands of DNA are made of alternating __sugar___ and __phosphate____ sections.
Attached to each __sugar____ is one of the four bases.
The DNA polymer is made up of repeating _____nucleotide_______ units.

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17
Q

In the complementary strands of DNA – which base is T always linked to?

A

A

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18
Q

Which organelle in the cytoplasm carries out protein synthesis?

A

Ribosome

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19
Q

What do carrier molecules bring to the organelle from the cytoplasm?

A

Amino acids

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20
Q

What happens in protein synthesis once the protein chain is complete?

A

The protein folds up into a unique shape.

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21
Q

What happens if a mutation codes for a slightly altered enzyme protein with a different shape?

A

The enzyme may no longer fit the substrate binding site

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22
Q

What can non-coding parts of DNA do?

A

Switch genes on or off and affect how genes are expressed

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23
Q

Complete the sentences below using one of the following words:
genotype phenotype homozygous gamete chromosome
The same alleles for a particular characteristic are described as _______ .
Mice fur can be described by its colour. This is known as the ______ .
The alleles for a particular characteristic determine its ______ .
The pollen of a rose plant can also be described as a male ______ .

A

The same alleles for a particular characteristic are described as homozygous
Mice fur can be described by its colour. This is known as the phenotype
The alleles for a particular characteristic determine its genotype
The pollen of a rose plant can also be described as a male gamete

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24
Q

What are the different forms of a gene called?

A

Alleles

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25
Q

Why is it easy to describe an organism’s phenotype for a particular characteristic but very difficult to state the genotype?

A

Most characteristics are a result of multiple genes interacting.

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26
Q

If two heterozygous tall plants were crossed 75 times, what proportion of the offspring would you expect to be short?

A

25% or 19

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27
Q

What is polydactyly and is it caused by inheriting a recessive or dominant allele?

A

A genetic disorder which results in having extra fingers or toes - dominant allele

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28
Q

How many chromosomes does this person have in a normal body cell?

A

23 pairs or 46

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29
Q

Is someone who is heterozygous for cystic fibrosis healthy?

A

Yes, they are a carrier but do not suffer from CF themselves

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30
Q

Many people feel opposed to the screening of embryos to identify the CF allele.
Suggest two reasons why they may feel this way.

A
  • Screening procedure may cause miscarriage or damage embryo/fetus
  • The embryo has a right to life
  • Screening is expensive and could be used for other purposes
  • Have to make moral/ethical or religious decisions as a result such as whether to terminate.
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31
Q

What does variation mean?

A

Variation means the differences in the characteristics of individuals in a population.

32
Q

Write a definition for evolution

A

A change in the inherited characteristics of a population over time, through a process of natural selection.

33
Q

What does the theory of evolution by natural selection state?

A

All species of living things have evolved from simple life forms that first developed more than 3 billion years ago.

34
Q

What is the definition of the term species?

A

A group of similar-looking individuals who can breed together and produce fertile offspring.

35
Q

Humans choose animals or plants to breed from based on usefulness or appearance.
List four characteristics which would be selected (two in plants and two in animals).

A

Disease resistance in crop plants
Animals which produce more meat or milk
Domestic dogs with a gentle nature
Large or unusual flowers

36
Q

What is a major disadvantage caused by selective breeding?

A

Can lead to inbreeding where some breeds are particularly prone to disease or inherited defects

37
Q

How often do mutations occur?

A

Continuously

38
Q

How likely is it that a mutation will lead to a new phenotype?

A

Very rare

39
Q

What is genetic engineering?

A

A process which involves modifying the genome of an organism by introducing a gene from another organism to give the desired characteristic.

40
Q

What human product is made by genetically engineered bacteria to treat diabetes?

A

Insulin

41
Q

What are plants more commonly called when they have had their genome modified?

A

GM crops

42
Q

How are the required genes isolated from the host?

A

Using an enzyme

43
Q

What is the role of a vector in genetic engineering?

A

Used to insert the gene into the required cells

44
Q

Name a common vector used in genetic engineering.

A

Bacterial plasmid/virus

45
Q

When in the life cycle must genes be transferred to the cells of animals, plants or microorganisms?

A

Early on in development so the new cells develop with the desired characteristic

46
Q

List three reasons which people are concerned about in relation to genetic engineering

A
  • Do not know the effect of using GM crops on populations of wild flowers and insects.
  • May kill insects which are needed to pollinate other plants.
  • Some people feel that the effects of eating GM crops on human health have not been fully explored.
  • For ethical reasons - should humans be inserting genes from one organism into a totally different organism?
47
Q

What is tissue culture?

A

Using small groups of cells from a part of a plant to grow identical new plants.

48
Q

Why is tissue culture important?

A

To preserve rare plant species commercially in nurseries to grow lots of new identical plants

49
Q

Why is an electric shock used in adult cell cloning?

A

To stimulate the egg cell to divide and form an embryo

50
Q

What is the term used to describe the technique gardeners use to produce many identical new plants from a parent plant?

A

Taking a cutting

51
Q

Name two pieces of evidence for Darwin’s theory of evolution through natural selection which mean it is now largely accepted.

A
  • Fossil record

- Knowledge of how resistance to antibiotics evolves in bacteria passing on of characteristics to offspring in genes

52
Q

What are fossils?

A

The remains of organisms from millions of years ago

53
Q

How many fossils be formed?

A

1) From parts of organisms that have not decayed

2) when parts of organism are replaced by minerals as preserved traces like footprints, burrows or rootlets.

54
Q

List two reasons why there are not many traces of early life on Earth.

A

Organisms were mainly soft bodied so little trace left

Any traces destroyed by geological activity

55
Q

What can be learned from studying fossils?

A

how much or how little organisms have changed as life developed on Earth

56
Q

What does an evolutionary tree show?

A

how organisms are related using current classification data or fossil data is a species is extinct

57
Q

What does it mean when we say an organism is extinct?

A

There are no remaining individuals of a species still alive

58
Q

List four factors which may contribute to the extinction of a species.

A

1) A change in food availability and the inability to find an alternative source.
2) Climate change
3) Creation of a new species by speciation that is better adapted to the environment
4) Human activity: Road/house building, mining, pollution, poaching, deforestation
5) A new predator or disease that a species cannot defend itself from.
6) Failure to breed successfully

59
Q

Why do bacteria evolve rapidly?

A

Because they reproduce at a rapid rate

60
Q

Name a bacterial pathogen which is resistant to several strains of antibiotics

A

MRSA

61
Q

Why are pharmaceutical companies not developing many new antibiotics ?

A

Very costly and takes a long time to develop.

62
Q

Name three things that can be done to reduce the rate of development of antibiotic resistance.

A

1) Doctors should not prescribe antibiotics for non serious or viral infections.
2) Patients must complete the course of antibiotics to ensure all bacteria are killed and none survive to mutate and become resistant.
3) Restrict the use of antibiotics in agriculture

63
Q

Name the seven groups that Linnaeus used to classify living organisms from largest to smallest.

A

Kingdom, phylum, class, order, family, genus, species

64
Q

What is the binomial naming system?

A

A method of scientifically naming animals using the genus and species.

65
Q

Carl Woese used information from chemical analysis to suggest a new method of classification. What is it called?

A

The three domain system

66
Q

List the groups that organisms are divided into using Carl Woese’s method.

A

Archaea
Bacteria
Eukaryota

67
Q

What theory did Charles Darwin propose?

A

The theory of evolution by natural selection.

68
Q

List three observations Darwin made which led him to propose his theory.

A

1) Individual organisms within a particular species show a wide range of variation for a characteristic
2) Individuals with characteristics most suited to the environment are more likely to survive to breed successfully
3) The characteristics that have enabled these individuals to survive are then passed on to the next generation

69
Q

What was Charles Darwin’s book called?

A

On the Origin of Species

70
Q

List three reasons why Charles Darwin’s theory was only partially accepted at the time.

A

1) The theory challenged the idea that God made all the animals and plants that lived on Earth
2) There was insufficient evidence at the time the theory was published to convince many scientists.
3) The mechanism of inheritance and variation was not known until 50 years after the theory was published.

71
Q

Jean Baptiste Lamarck put forward his theory of evolution. What was his idea?

A

that changes occur in an organisms life time and these can be inherited.

72
Q

Alfred Wallace also put forward his theory of evolution by natural selection independently to Darwin but what work is he best known for?

A

His work on warning colouration in animals and his theory of speciation

73
Q

List the steps needed for a new species to be formed.

A

1) Populations of the same species become isolated
2) Environmental conditions differ for each population
3) Individuals in each population most suited to the environment breed successfully
4) Over time each population will have greater differences in their genotype.
5) If two populations of one species become so different in phenotype that they can no longer interbreed and produce fertile offspring – 2 new species have been formed.

74
Q

What did Gregor Mendel observe when he carried out breeding experiments on pea plants?

A

Inheritance of each characteristic is determined by units that are passed onto the next generation unchanged.

75
Q

What was discovered in the late 19th century which helped to develop our understanding of genetics further?

A

The behaviour of chromosomes in cell division

76
Q

When was the structure of DNA determined and the mechanism of gene function determined?

A

Mid 20th century