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BIOLOGY-EVIE > Topic 6- Inheritance, Variation and Evolution > Flashcards

Topic 6- Inheritance, Variation and Evolution Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what’s a gene

A

small section of dna found on a chromosome

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2
Q

what is DNA made of

A

polymer, 2 strands coiled up in shape of double helix

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3
Q

chromosomes come in…

A

pairs (usually)

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4
Q

where is DNA found

A

nucleus of animal and plant cells

in long structures called chromosomes

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5
Q

what does DNA contain

A

coded info

all the instructions for an organism to work

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6
Q

what is DNA

A

the chemical that all of the genetic material in a cell is made up of

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7
Q

what are chromosomes?

A

long molecules of DNA

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8
Q

give examples of asexual reproduction in certain species of plants

A

bulbs

runners

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9
Q

how do ‘runners’ work

A

theyre asexual
stems grow horizontally on the surface of soil away from plant
at various points along the runner, new plants form, identical to original plant

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10
Q

what do sexually produced spores do

A

introduce variation- often produced in response to unfavorable change in environment to increase survival

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11
Q

what do a-sexually produced spores do

A

form fungi that are generally identical to parent fungus

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12
Q

what are fungi spores

A

things released by fungus which can become new fungi when they land in a suitable place

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13
Q

when does a parasite to asexual reproduction

A

in the human host

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14
Q

when does a parasite do sexual reproduction

A

in the mosquito

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15
Q

advantages of asexual reproduction

A
  • only one parent needed
  • less energy- dont need to find a mate
  • faster
  • many identical offspring can be produced in favourable conditions
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16
Q

advantages of sexual reproduction

A
  • variation in offspring
  • survival advantage
  • natural selection- bettera dapted to environment, better chance of survival and will breed successfully
  • selective breeding
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17
Q

as an embryo starts to develop, the cells start to…

A

differentiate into the different types of specialised cells that make up a whole organism

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18
Q

after the gametes(sperm and egg)have fused, what happens

A

the new cell divides by mitosis to copy itself into the embryo.

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19
Q

what happens in meiosis

A

1- cell duplicates genetic info

2- this forms two armed chromosomes, the chromosomes arrange into pairs

3- FIRST DIVISION- pairs line up in centre of cell

4- pairs pulled apart- each new cells has one copy of each chromosome, some fathers, some mothers

5- SECOND DIVISION- chromosomes line up again in centre. Arms pulled apart

6- produces 4 genetically different gametes

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20
Q

what does meiosis produce

A

gametes

cells which have half the normal number of chromosomes

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21
Q

humans reproduce…

A

sexually

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22
Q

what reproduces asexually

A

bacteria, some plants, some animals

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23
Q

what does asexual reproduction happen by, and how?

A

MITOSIS- an ordinary cell makes a new cell by dividing in two

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24
Q

what happens in asexual reproduction

A

ONE parent
No gamete fusion or mix of chromosomes
No genetic variation between parent and offspring
They’re clones/genetically identical

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25
Q

what type of cells does asexual reproduction produce?

A

gentically identical

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26
Q

whats a flowers version of sperm

A

pollen

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27
Q

what does the mixture of genetic info produce

A

variation in the offspring

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28
Q

what is fertilisation

A

egg meets sperm

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29
Q

what does the offspring contain

A

a mixture of parents genes

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30
Q

what happens to the sperm and egg

A

the egg and sperm cell fuse together (fertilisation) to form a cell with the full number of chromosomes

1/2 mothers 1/2 fathers

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31
Q

how many chromosomes does each gamete contian

A

23 chromosomes (half the number in a normal cell)

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32
Q

what are gametes and how are they produced in sexual reproduction

A

gametes are sperm and the egg

produced by meiosis

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33
Q

what happens in sexual reproduction

A

genetic info from 2 organisms (m and d) is combines to produce offspring which are genetically different to either parent

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34
Q

what type of cells does sexual reproduction produce

A

genetically different

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35
Q

what is a mutation

A

a random change in the genetic code

they sometimes can be inherited

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36
Q

give examples of proteins and their function

A

enzymes (biological catalysts)
hormones- carry messages around the body eg. insulin regulated blood sugar levels

structural proteins- physically strong eg. collagen strengthens ligaments and cartilage

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37
Q

what happens when the chain of amino acids in made into proteins

A

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

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38
Q

how are proteins made

A

by using a molecule called MRNA
the MRNA acts as a messenger between the DNA and the ribosome
the correct amino acids are brought to the ribosomes in the correct order by carrier molecules

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39
Q

where are proteins made

A

in the cytoplasm on tiny structures called ribosomes

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40
Q

what carries the code to the ribosomes

A

mRNA

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41
Q

what do the parts of DNA that don’t code for proteins do

A

switch genes on and off

control whether or not a gene is expressed (used to make a protein)

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42
Q

what join together to make various proteins depending on the order

A

amino acids

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43
Q

how many bases in a gene codes for an amino acid

A

3

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44
Q

what does the order of bases in a gene determine

A

the order of amino acids in a protein

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45
Q

describe complimentary base pairing

A

A pairs with T

G pairs with C

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46
Q

explain how the sugar and phosphate molecules alternate

A

one of 4 different bases, A,T,G,C joins to each sugar

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

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47
Q

what dose the sugar and phosphate molecule in the nucleotides form

A

a ‘backbone’ to the DNA strands

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48
Q

what does each nucleotide consist of

A

1 sugar molecule
1 phosphate molecule
1 base

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49
Q

what is DNA

A

polymer made of lots of repeating units called nucleotides

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50
Q

why is the human genome really important for scientists

A

to identify genes linked to disease
knowing which genes link to inherited diseases- develop effective treatments
trace migration

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51
Q

what is a genome

A

entire set of genetic material in an organism

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52
Q

what does DNA also determine

A

what proteins in the cell produces eg. haemoglobin, keratin

this determines what type of cell it is eg. red blood, skin cell

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53
Q

how many amino acids are there

A

20

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54
Q

what dose each gene code for

A

a particular sequence of amino acids which are put together to make a specific protein

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55
Q

what happens if there’s a mutation in the non-coding DNA

A

then it can alter how genes are expressed

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56
Q

describe two wasy a mutation can affect the shape of a protein

A

if the enzymes ACTIVE SITE changes shape, the substrate can’t bind to it

structural proteins loose strength

57
Q

how does a mutation affect a protein

A

most only change it to a small extent

some can seriously affect a protein and CHANGE ITS APPEARENCE.

58
Q

what do mutations do

A

change DNA base sequence

Change shape of amino acid

changes in protein

59
Q

when can mutations occur

A

spontaneously eg.chromosome doesn’t replicate properly

when exposed to certain substances or certain types of radiation, chances increase

60
Q

what are the three different types of mutation

A

insertions, deletions, substitutions

61
Q

what is insertion

A

where a new base is inserted into the DNA base sequence where it shouldnt be, which has a knock on affect, changing multiple amino acids

62
Q

what is deletion

A

when a random base is DELETED form the DNA base sequence

63
Q

what is substitution

A

when a random base in the DNA base sequence is changed to a different base

64
Q

characteristics are controlled by a single gene

A

fur colour

in mice; and red-green colour blindness in humans

65
Q

what are alleles

A

different versions of genes

66
Q

what’s genotype means

A

the combination of alleles you have

67
Q

whats your phenotype

A

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

68
Q

when are dominant and recessive alleles expressed

A

A dominant allele is always expressed, even if only one copy is present.
A recessive allele is only expressed if two copies are present (therefore
no dominant allele present).

69
Q

If the two alleles present are the same the organism is

A

homozygous

70
Q

if the alleles are different they are

A

heterozygous.

71
Q

what are most characteristics a result of

A

multiple genes interacting, rather

than a single gene.

72
Q

how many pairs of chromosomes do the human body cells contain

A

Ordinary human body cells contain 23 pairs of chromosomes

73
Q

How many pairs control characteristics only

A

22 pairs

74
Q

how many of the pairs carries the

genes that determine sex.

A

one

75
Q

• In females the sex chromosomes are…

A

the same (XX)

76
Q

• In males the chromosomes are…

A

different (XY)

77
Q

some disorders are caused by the

inheritance of what?

A

certain alleles

78
Q

What disorder is caused by a dominant

allele.

A

Polydactyly (having extra fingers or toes)

79
Q

What disorder is caused by a recessive allele

A

Cystic fibrosis (a disorder of cell membranes)

80
Q

FOR embryo screening

A

helps stop suffering
treating disorders costs the government and the taxpayers a lot of money
laws to stop it going too far

81
Q

AGAINST embryonic screening

A

implies the baby is less worthy of life- prejudice
lead to designer babies
screening is expensive

82
Q

what were mendel’s three main conclusions about heredity

A
  • characteristics in plants are determined by hereditary units
  • hereditary units are passed on to offspring unchanged from both parents, one unit from each parent.
  • hereditary units can be dominant or recessive- if an individual has both the dominant and the recessive unit for a characteristic, the dominant characteristic will be expressed.
83
Q

what is variation

A

Differences in the characteristics of individuals in a population

84
Q

how is genetic variation caused

A

when there is a combining of genes form two parents- no two of the species are genetically identical

85
Q

which characteristics are determined only by genes in animals?

A

hair and eye colour, blood group, inherited disorders

86
Q

what is environmental variation

A

when the environment causes differences between members of the same species

87
Q

what is variation due to

A
  • the genes they have inherited (genetic causes)
  • the conditions in which they have developed (environmental causes)
  • a combination of genes and the environment.
88
Q

what effect does mutations have on the phenotype

A

most have
no effect on the phenotype; some influence phenotype; very few
determine phenotype.

89
Q

If the new phenotype is suited to an environmental change, what can it lead to?

A

a relatively rapid change in the species.

90
Q

what is evolution

A

all of today’s species have evolved form simple life forms that first started to develop over 3 bn yrs ago

91
Q

what does the theory of evolution by natural selection state

A

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

92
Q

what’s speciation (new species being formed)

A

when two populations of one species become so different in phenotype that they can no longer interbreed to produce fertile offspring

93
Q

what did darwin conclude

A

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

94
Q

why was Darwin’s theory only gradually accepted

A

• the theory challenged the idea that God made all the animals and
plants that live on Earth
• there was insufficient evidence at the time the theory was published
to convince many scientists
• the mechanism of inheritance and variation was not known until
50 years after the theory was published.

95
Q

what is extinction

A

when no individuals of a new species remain

96
Q

why do species become extinct

A

the environment changes too quickly- e. destruction of habitat
new predator kills them all (humans hunting)
new disease kills them all
can’t compete for food
catastrophic event (eg. volcano, collision with an asteroid)

97
Q

What was Lamarck’s ideas

A

-changes that an organism aquires during its lifetime will be passed on to its offspring

98
Q

why was Lamarck’s hypothesis eventually rejected

A

experiments didnt support it

99
Q

why was Darwin’s hypothesis eventually accepted

A

fossil evidence, discovery of bacteria evolution and it provided an explanation of how organisms born with beneficial characteristics can pass them on

100
Q

what does selective breeding involve

A

choosing parents with the desired
characteristic from a mixed population. They are bred together. From the
offspring those with the desired characteristic are bred together. This
continues over many generations until all the offspring show the desired
characteristic.

101
Q

what is selective breeding

A

humans breed plants and animals for particular genetic characteristics.

102
Q

how long has selective breeding been around

A

Humans have been doing this for thousands of years since they first bred food crops from wild plants and domesticated animals.

103
Q

name some desired characteristics in selective breeding

A
  • Disease resistance in food crops.
  • Animals which produce more meat or milk.
  • Domestic dogs with a gentle nature.
  • Large or unusual flowers.
104
Q

what can selective breeding lead to

A

‘inbreeding’ where some breeds are

particularly prone to disease or inherited defects (reduction in the gene pool)

105
Q

how does genetic engineering work

A

• enzymes are used to isolate the required gene; this gene is inserted
into a vector, usually a bacterial plasmid or a virus
• the vector is used to insert the gene into the required cells
• genes are transferred to the cells of animals, plants or
microorganisms at an early stage in their development so that they
develop with desired characteristics.

106
Q

why have plant crops been genetically engineered

A

to be resistant to diseases or to produce bigger better fruits.

107
Q

why have bacterial cells been genetically engineered

A

to produce useful

substances such as human insulin to treat diabetes.

108
Q

give a simple definitiion for genetic enginerring

A

genes from the chromosomes of humans and
other organisms can be ‘cut out’ and transferred to cells of other
organisms.

109
Q

what are GM crops made to be

A

resistant to insect attack or to herbicides

110
Q

Give some examples of worries for Genetic engineering

A

long term effects- changing an organisms genes may accidentally create unplanned problems, which could get passed on to the future generations

111
Q

Pros of genetic engineering

A

increase yield
foods with specific nutrients in- ‘golden rice’
already being grown in some places perfectly fine

112
Q

Cons of genetic engineering`

A

Could affect no. of wild flowers and therefore the population of insects- reducing farmland biodiversity

Some people feel the effects of eating GM crops on
human health have not been fully explored.

transplanted genes may get out into the natural environment - could lead to ‘superweed’ variety

113
Q

What is modern medical research is exploring the possibility of

A

genetic modification to overcome some inherited disorders.

114
Q

what two ways can plants be cloned by

A

tissue culture and cuttings

115
Q

what is tissue culture

A

using small groups of cells from part of a plant to grow
identical new plants.
This is important for preserving rare plant species
or commercially in nurseries.

116
Q

what is the method of ‘cuttings’

A

method used by gardeners to produce

many identical new plants from a parent plant.

117
Q

explain Embryo transplants

A

splitting apart cells from a developing animal
embryo before they become specialised, then transplanting the identical
embryos into host mothers.

118
Q

What is Adult cell cloning

A

• The nucleus is removed from an unfertilised egg cell.
• The nucleus from an adult body cell, such as a skin cell, is inserted
into the egg cell.
• An electric shock stimulates the egg cell to divide to form an embryo.
• These embryo cells contain the same genetic information as the adult
skin cell.
• When the embryo has developed into a ball of cells, it is inserted into
the womb of an adult female to continue its development.

119
Q

What are some issues of cloning

A

reduced gene pool- fewer different alleles in a population- may be no allele in population to fight off a specific disease

cloned animals might not be as healthy as normal ones

humans may be cloned in the future- unsuccessful attempts could lead to disabled children

120
Q

positive things about cloning

A

leads to more knowledge of development of embryo and age-related disorders

preserve endangered species

121
Q

what are fossils

A

‘remains’ of organisms from millions of years ago, which are found in rocks.

122
Q

how can fossils be formed

A
  • from preservation in a place where decay cannot happen
  • parts of the organism are replaced by minerals as they decay
  • from casts and impressions
123
Q

why cant scientists be certain

about how life began on Earth

A

Many early forms of life were soft-bodied, so

have left few traces behind. Few traces have been mainly destroyed by geological activity

124
Q

what is a species

A

a group of similar organisms that can reproduce to give fertile offspring

125
Q

which two ways lead to speciation

A

Natural selection and isolation

126
Q

what is isolation

A

where populations of a species are separated

Eg. floods and earthquakes can cause physical barriers

conditions on either side will be different eg. climate

different characteristics will become more common in each population due to NATURAL SELECTION

127
Q

Explain how natural selection leads to speciation

A

each population has genetic variation and a wide range of alleles

better adapted animals have better chance of survival, therefore have better chance to breed successfully

‘good’ alleles will pass on to the next generation

EVENTUALLY THE TWO SIDES CAN NO LONGER BREED WITH EACH OTHER

128
Q

what is Alfred Wallace famous for

A
  • came up with the idea of natural selection
  • worked with Darwin- prompted Darwin to publish ‘On the Origin of Species’- 1859
  • provided evidence- relalised species had ‘warning colours’
129
Q

How does antibiotic resistance work?

A

Mutations of bacterial pathogens produce new strains.

Some strains might be resistant to antibiotics- so are not killed.

They survive and reproduce, so the population of the resistant strain increases.

The resistant strain will then spread because people are not immune to it and there is no effective treatment.

130
Q

Why can bacteria can evolve rapidly?

A

because they reproduce at a fast rate.

131
Q

give an example of a superbug which is not resistant to bacteria

A

MRSA

132
Q

how can we reduce antibiotic resistant strains?

A
  • do not prescribe antibiotics inappropriately
  • patients should complete their course of antibiotics
  • agricultural use of antibiotics should be restricted
133
Q

What is the system developed by Carl Linnaeus

A

where living things are classified into groups depending on their structure and characteristics

134
Q

Name the order of the classification system

A

kingdom, phylum, class, order,

family, genus and species

135
Q

Why were new models of clamssification made

A

Evidence of internal structures became more developed due to improvements in microscope.

Andthe understanding of biochemical processes progressed.

136
Q

What did Carl Woese do

A

proposed the three domain system,

  • archaea (primitive bacteria usually living in extreme environments)
  • bacteria (true bacteria)
  • eukaryota (which includes protists, fungi, plants and animals).
137
Q

how does the binomial system work

A

first part- genus
second part-species

Eg. Homo-Sapien

138
Q

How are Evolutionary Trees used by scientists

A

method used by scientists to show how they
believe organisms are related.

They use current classification data for living organisms and fossil data for extinct organisms.

BIOLOGY-EVIE (8 decks)

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