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Master Separate Science - Biology > Separate Biology - 4.6 > Flashcards

Separate Biology - 4.6 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What type of cell division leads to identical cells being formed?

A

Mitosis

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2
Q

What type of cell division leads to non-identical cells being formed?

A

Meiosis

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3
Q

What does sexual reproduction, in animals, involve?

A

The joining (fusing) of male and female gametes (sperm and egg)

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4
Q

What does sexual reproduction, in plants, involve?

A

The joining (fusing) of gametes (pollen and egg cells)

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5
Q

What does sexual reproduction lead to and why?

A

Variety in the offspring as there is mixing of genetic information

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6
Q

What is asexual reproduction?

A

One parent (no fusion or mixing of genetic information) leading to genetically identical offspring

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7
Q

What is a clone?

A

Genetically identical offspring (a result of asexual reproduction)

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8
Q

What does meiosis do to the number of chromosomes in the gamete?

A

It halves it (46 to 23)

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9
Q

What happens to the number of chromosomes during fertilisation?

A

It doubles (male and female gametes both have 23 chromosomes, combining to make 46)

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10
Q

What key stages occur when a cell divides to form gametes (meiosis)?

A
  1. Copies of the genetic information are made
  2. The cell divides twice forming four gametes (each with a single set of chromosomes)
  3. All the gametes are genetically different from each other
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11
Q

Separate Q. What are the advantages of sexual reproduction?

A
  • Produces variation
  • If the environment changes, variation gives a survival advantage by natural selection (taken advantage of by human selective breeding)
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12
Q

Separate Q. What are the advantages of asexual reproduction?

A
  • Only one parent needed
  • More time and energy efficient (no mate to find)
  • Faster than sexual reproduction
  • Many identical offspring can be produced when conditions are favourable
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13
Q

Separate Q. How do malarial parasites reproduce?

A

Asexually in the human host but sexually in the mosquito

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14
Q

Separate Q. How do (many) fungi reproduce?

A

Asexually by spores but also sexually to allow for variation

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15
Q

Separate Q. How do (many) plants reproduce?

A

Sexual reproduction: Via seed dispersal

Asexual reproduction: Via runners (e.g. strawberry plants) or bulb division (e.g. Daffodil or potato plants).

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16
Q

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

A

DNA

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17
Q

What is the structure of DNA?

A

A polymer made up of two strands forming a double helix

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18
Q

What is DNA contained in?

A

Chromosomes

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19
Q

What is a gene?

A

A small section of DNA on a chromosome

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20
Q

What does a gene code for?

A

A particular sequence of amino acids, which make specific proteins

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21
Q

What is the genome of an organism?

A

The entire genetic material of that organism

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22
Q

Why is having the human genome sequence important?

A

It will be of benefit to medicine

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23
Q

Why is understanding the human genome important?

A
  • Genes linked to different types of disease can be searched for
  • Inherited disorders can be understood / treated
  • Migration patterns of the past can be traced
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24
Q

Separate Q. DNA as a polymer is made from how many nucleotides (and what are these)?

A

4x different nucleotides – each consists of a common sugar and phosphate group with one of four different bases attached to the sugar

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25
Q

Separate Q. What are the four bases DNA contains?

A

A, T, C and G

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26
Q

Separate Q. How does a particular amino acid get coded?

A

A sequence of three bases is the code – the order of bases controls the order in which amino acids are assembled to produce a particular protein

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27
Q

Separate Q. What do long strands of DNA consist of?

A

Alternating sugar and phosphate sections (attached to each sugar is one of four bases)

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28
Q

Separate Q. What is the DNA polymer made up of?

A

Repeating nucleotide units

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29
Q

Separate Higher Q. How may genetic variants influence the phenotype in coding DNA?

A

The activity of a protein might be altered

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30
Q

Separate Higher Q. How may genetic variants influence the phenotype in non-coding DNA?

A

How the genes are expressed may be altered

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31
Q

Separate Higher Q. Where are proteins synthesised?

A

On ribosomes (according to a template)

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32
Q

Separate Higher Q. How are proteins synthesised?

A

Carrier molecules bring specific amino acids to add to the growing protein chain (in the correct order))

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33
Q

Separate Higher Q. What does the unique shape of a folded protein chain allow for?

A

The unique shape enables proteins to do their job as enzymes, hormones or forming structures (such as collagen)

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34
Q

Separate Higher Q. What are proteins used for?

A
  • Enzymes
  • Hormones
  • Forming structures (e.g. collagen)
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35
Q

Separate Higher Q. Mutations occur continuously – what is the outcome for most of these?

A

Most do not alter the protein (or only alter it slightly so that the appearance / function is not changed)

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36
Q

Separate Higher Q. What might happen if a mutation codes for an altered protein (with a different shape)?

A

An enzyme may no longer fit the substrate binding site / a structural protein may lose its strength

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37
Q

Separate Higher Q. What do non-coding parts of DNA do?

A

Not all parts of DNA code for proteins – non-coding parts can switch genes on/off

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38
Q

Separate Higher Q. What can variations in non-coding parts of DNA lead to?

A

How genes are expressed may be affected (as non-coding parts of DNA can switch genes on/off)

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39
Q

Explain the term: gamete

A

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

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40
Q

Explain the term: chromosome

A

A long molecule of DNA, found in the nucleus of a cell, which carries genes

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41
Q

Explain the term: gene

A

A short section of DNA, found on a chromosome, carrying the instructions needed to make a protein (and so controls the development of a characteristic)

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42
Q

Explain the term: allele

A

An alternative version of a gene

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43
Q

Explain the term: dominant

A

The allele for the characteristic that’s shown by an organism if two different alleles are present for that characteristic

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44
Q

Explain the term: recessive

A

An allele whose characteristic only appears in an organism if there are two copies present

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45
Q

Explain the term: homozygous

A

Where an organism has two alleles for a particular gene that are the same

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46
Q

Explain the term: heterozygous

A

Where an organism has two alleles for a particular gene that are different

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47
Q

Explain the term: genotype

A

What alleles and organism has, e.g. Tt

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48
Q

Explain the term: phenotype

A

The characteristics an organism has, e.g. tall

49
Q

Give an example of characteristics controlled by a single gene

A

Fur colour in mice / red-green colour blindness in humans

50
Q

What controls the phenotype (what is expressed)?

A

Alleles present (or genotype) operating at a molecular level to develop characteristics expressed (as a phenotype)

51
Q

Which allele is always expressed?

A

The dominant (even if only one copy is present)

52
Q

What are most characteristics a result of?

A

Multiple genes interacting (rather than a single gene)

53
Q

Complete a Punnett square for the % chance of having a boy or girl

A
54
Q

What is polydactyly?

A

An inherited disorder (extra fingers or toes) caused by a dominant allele

55
Q

What is cystic fibrosis?

A

An inherited disorder (cell membrane issues) caused by a recessive allele

56
Q

How many pairs of chromosomes are found in ordinary human body cells?

A

23 pairs

57
Q

22 pairs of chromosomes control characteristic, but what does the 23rd pair control?

A

The gene which determines sex (XX in female and XY in male)

58
Q

How does the phenotype of an organism develop?

A

The interaction between the genome and environment influence development of the phenotype

59
Q

What is variation?

A

Differences in the characteristics of individuals in a population

60
Q

What can cause variation?

A
  • The genes inherited (genetic cause)
  • The conditions in which the organism has developed (environmental cause)
  • A combination of genes and environment
61
Q

Within a population of a species, what usually exists?

A

Extensive genetic variation

62
Q

How do variants in a species arise?

A

Mutations: most have no effect on phenotype, some influence phenotype, and very few determine phenotype

63
Q

If a mutation leads to a new phenotype, suited to an environmental change, what might occur?

A

Relatively rapid change in the species

64
Q

What is evolution?

A

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

65
Q

What is the driving force of evolution?

A

Natural selection

66
Q

What is the theory of evolution by natural selection?

A

All species of living things have evolved from simple life forms, that first developed more than three billions years ago

67
Q

Variants that give rise to phenotypes best suited to their environment causes what?

A

Evolution, occurring through natural selection

68
Q

How do new species form?

A

If two populations of one species become so phenotypically different they cannot interbreed (to produce fertile offspring) then they have formed two new species

69
Q

What is selective breeding?

A

Selective breeding is artificial selection – humans breed plants and animals for particular genetic characteristics

70
Q

What does selective breeding involve?

A

Choosing parents with the desired characteristics from a mixed population, which are bred, and offspring with desired characteristics are bred

71
Q

What characteristics might be chosen during selective breeding

A
  • Disease resistance in food crops
  • Animals which produce more milk / meat
  • Domestic dogs of a gentle nature
  • Large / unusual flowers
72
Q

What can selective breeding lead to?

A

Inbreeding – some breeds are prone to diseases or inherited defects

73
Q

What is genetic engineering?

A

A process involving modifying the genome or an organism by introducing a gene from another organism: giving a desired characteristic

74
Q

How have plant crops been genetically engineered?

A

To be resistant to disease / produce bigger and better fruits

75
Q

How have bacterial cells been genetically engineered?

A

To produce useful substances such as human insulin (treating diabetes)

76
Q

How does genetic engineering occur?

A

Genes from chromosomes are ‘cut out’ and transferred to cells of other organisms

77
Q

What are genetically modified (GM) crops?

A

Crops that have had their genes modified: resistance to insect attack / herbicides for example (generally show yield increase)

78
Q

What concerns are there about GM crops?

A

The effect on populations of wild flowers and insects / human health (not being fully explored)

79
Q

How is modern medical research utilising genetic modifications?

A

To overcome some inherited diseases

80
Q

Higher Q. How are enzymes used in genetic engineering?

A

Enzymes isolate the required gene, which is inserted into a vector (usually a bacterial plasmid / virus)

81
Q

Higher Q. How are vectors used in genetic engineering?

A

Enzymes isolate the required gene, which is inserted into a vector (usually a bacterial plasmid / virus)

82
Q

Higher Q. How are genes transferred during genetic engineering?

A

The bacterial plasmid / virus vector inserts the gene into the required cells

83
Q

Higher Q. Why are genes transferred at an early stage of the organism’s development during genetic engineering?

A

So they develop with the desired characteristic

84
Q

Separate Q. What is tissue culture?

A

Small groups of cells from part of a plant grow to form identical new plants

85
Q

Separate Q. Why is tissue culture important?

A

It can preserve rare plant species or be used commercially in nurseries

86
Q

Separate Q. What is a cutting?

A

A small part of a plant that is taken from a parent plant to produce many identical new plants.

87
Q

Separate Q. What is embryo transplant?

A

Splitting apart cells from a developing embryo before they become specialised and transplanting these identical embryos into host mothers

88
Q

Separate Q. What is adult cell cloning?

A

The nucleus is removed from an unfertilised egg and replaced with a nucleus from an adult body cell – electrical shock stimulates the egg cell to divide, forming an embryo

89
Q

Separate Q. In adult cell cloning, what do the embryo cells contain?

A

The same genetic information as the adult body cell from where the nucleus came from.

90
Q

Separate Q. In adult cell cloning, where does the embryo which has developed into a ball of cells go?

A

It is inserted into the womb of an adult female to continue its development.

91
Q

Separate Q. Who proposed the theory of evolution by natural selection?

A

Charles Darwin

92
Q

Separate Q. What are the key principles of the theory of evolution by natural selection?

A
  1. Individual organisms with a particular species show a wide range of variation for a characteristic
  2. Individuals with characteristic most suited to the environment are more likely to survive and breed
  3. Characteristics are then passed to the next generation
93
Q

Separate Q. Where did Charles Darwin publish his ideas about evolution?

A

In the book On the Origin of Species (1859) which was greeted with much controversy.

94
Q

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

A
  • The theory challenged the idea that God made all the animals and plants
  • There was insufficient evidence at the time
  • The mechanisms of inheritance and variation was not known until 50 years after the publication
95
Q

Separate Q. What did Jean-Baptiste Lamarck theorise?

A

Changes occur in an organism during its lifetime which can then be inherited

96
Q

Separate Q. What did Alfred Russel Wallace propose?

A

He independently proposed the theory of evolution by natural selection along with Darwin

97
Q

Separate Q. What was Wallace best known for?

A

He worked worldwide gathering evidence for evolutionary theory – best known for his work on warning colourations and his theory of speciation

98
Q

Separate Q. What did Gregor Mendel discover?

A

Inheritance of each characteristic is determined by ‘units’ that are passed on to descendants unchanged

99
Q

Separate Q. When was the behaviour of chromosomes during cell division observed?

A

The late 19th Century

100
Q

Separate Q. When were Mendel’s ‘units’ and chromosomes linked?

A

In the early 20th Century: chromosomes and the ‘units’ behaved in similar ways leading to the ‘units’, now known as genes, being located on the chromosomes

101
Q

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

A

The mid-20th Century

102
Q

What evidence is there for evolution?

A

Fossils and antibiotic resistance in bacteria

103
Q

What are fossils?

A

The ‘remains’ of an organism from millions of years ago, found in rocks

104
Q

How may fossils be formed?

A
  • From parts of organisms that have not decayed because one or more the conditions for decay was absent
  • Parts of the organism are replaced by minerals as they decay
  • Preserved traces (footprints / burrows etc…)
105
Q

Why are there very few traces of early life forms?

A

They were soft-bodies (fossil record incomplete)

106
Q

What do fossils show?

A

How much / how little different organisms have changed as life developed on Earth

107
Q

What is extinction?

A

When there are no remaining individuals of a species still alive

108
Q

What may cause extinction of a species?

A
  • Environmental changes
  • New predators
  • New diseases
  • Catastrophic events
  • Unable to compete
109
Q

Why can bacteria evolve rapidly?

A

They reproduce at a fast rate

110
Q

How do new strains of bacteria occur?

A

Mutations: some strains may be resistant to antibiotics so are not killed and the resistant strains rises

111
Q

What is MRSA resistant to?

A

Antibiotics

112
Q

How can antibiotic resistance be reduced?

A
  • Reduce prescription of antibiotics, especially when inappropriate (e.g. for a viral infection)
  • Patients should complete course of antibiotics so all bacteria are killed
  • Restriction of agricultural antibiotic use
113
Q

What issues are there with antibiotic development?

A

It is costly and slow – it is unlikely to keep up with the emergence of new resistant strains

114
Q

What did Carl Linnaeus develop?

A

A classification systems, based on structures and characteristics

115
Q

How did Carl Linnaeus characterise living organisms?

A

Kingdom > phylum > class > order > family > genus > species

116
Q

How are organisms named?

A

The binomial system of genus and species

117
Q

What caused new models of classification to be proposed?

A

Evidence of internal structures (microscopes) and biochemical processes were better understood

118
Q

What is the ‘three-domain system’?

A

Carl Woese divided organisms into:

  • Archaea (primitive bacteria)
  • Bacteria (true bacteria)
  • Eukaryota (protists, fungi, plants and animals)
119
Q

How can the relation of organisms be shown?

A

Evolutionary trees – current classification data for living organisms and fossil data for extinct organisms is used

Master Separate Science - Biology (7 decks)

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