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Biology Flashcards - OCR 21st Century > B4 - Using Food and Controlling Growth > Flashcards

B4 - Using Food and Controlling Growth Flashcards

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1
Q

What is respiration?

A

What is respiration?

A process that releases energy in the
form of ATP from the breakdown of
glucose

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2
Q

What is ATP?

A

What is ATP?

It is a short term energy store in all cells
and is described as the universal energy
carrier.

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3
Q

Why does respiration occur continuously

in living cells?

A

Why does respiration occur continuously in living
cells?
ATP is required for many essential processes in living cells e.g. movement, homeostasis and active transport.

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4
Q

What type of reaction is respiration?

A

What type of reaction is respiration?

It is an exothermic reaction that releases
energy in the form of heat.

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5
Q

Where do plants get the glucose

required for respiration?

A

Where do plants get the glucose required for
respiration?
They produce their own glucose during photosynthesis.

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6
Q

Where do animals get the glucose

required for respiration?

A

Where do animals get the glucose required for
respiration?
From the breakdown of carbohydrates that they have ingested

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7
Q

What is aerobic respiration?

A

What is aerobic respiration?

Respiration in the presence of oxygen that forms ATP from the breakdown of glucose

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8
Q

Write the word equation for aerobic

respiration

A

Write the word equation for aerobic respiration

glucose + oxygen → carbon dioxide + water (+ATP)

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9
Q

Write the symbol equation for aerobic

respiration

A

Write the symbol equation for aerobic respiration

C6H12O6+ 6O2 → 6CO2 + 6H2O (+ATP)

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10
Q

What does aerobic respiration require?

A

What does aerobic respiration require?
Glucose, C6H12O6
Or another respiratory substance e.g. lipids, proteins
Oxygen gas, O2

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11
Q

What does aerobic respiration produce?

A

What does aerobic respiration produce?
Carbon dioxide gas, CO2
Water, H2O
ATP

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12
Q

Where does aerobic respiration take

place in eukaryotic cells?

A

Where does aerobic respiration take place in
eukaryotic cells?
In the cytoplasm and mitochondria

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13
Q

Where does aerobic respiration take

place in prokaryotic cells?

A

Where does aerobic respiration take place in
prokaryotic cells?
In the cytoplasm

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14
Q

What is anaerobic respiration?

A

What is anaerobic respiration?

Respiration that takes place without oxygen and forms ATP from the breakdown of glucose

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15
Q

When may anaerobic respiration take

place in human cells?

A

When may anaerobic respiration take place in
human cells?

During vigorous exercise

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16
Q

When may anaerobic respiration take

place in plant cells?

A

When may anaerobic respiration take place in plant
cells?
If the soil becomes waterlogged

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17
Q

When may anaerobic respiration take

place in bacteria?

A

When may anaerobic respiration take place in
bacteria?
When bacteria enter puncture wounds (little oxygen available)

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18
Q

Where does anaerobic respiration take

place?

A

Where does anaerobic respiration take place?

It takes place in the cytoplasm of eukaryotic and prokaryotic cells.

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19
Q

What does anaerobic respiration

require?

A

What does anaerobic respiration require?
Glucose, C6H12O6
Or another respiratory substance e.g. lipids, proteins

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20
Q

Write the word equation for anaerobic

respiration in muscle cells

A

Write the word equation for anaerobic respiration in
muscle cells
glucose → lactic acid (+ ATP)

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21
Q

Why may anaerobic respiration in

muscle cells eventually stop?

A

Why may anaerobic respiration in muscle cells
eventually stop?
Lactic acid build-up inhibits anaerobic
respiration

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22
Q

What are the symptoms of lactic acid

build-up?

A

What are the symptoms of lactic acid build-up?

Cramp and fatigue

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23
Q

Write the word equation for anaerobic

respiration in yeast cells

A

Write the word equation for anaerobic respiration in
yeast cells
glucose → ethanol + carbon dioxide (+ATP)

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24
Q

What is the problem associated with

ethanol build-up in yeast cells?

A

What is the problem associated with ethanol build-up
in yeast cells?
Ethanol is toxic to yeast cells

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25
Q

Is aerobic or anaerobic respiration more

efficient? Explain why

A

Is aerobic or anaerobic respiration more efficient?
Explain why
Aerobic respiration is more efficient as it produces 32 molecules of ATP in comparison to anaerobic respiration which produces 2 molecules of ATP.

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26
Q

Why does anaerobic respiration release

less energy than aerobic respiration?

A

Why does anaerobic respiration release less energy
than aerobic respiration?

Glucose is only partially broken down in
anaerobic respiration.

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27
Q

What is magnification?

A

What is magnification?

The number of times bigger an image appears compared to the size of the specimen

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28
Q

How can the total magnification of an

image be calculated from lens powers?

A

Total magnification =

eyepiece lens magnification x objective lens magnification

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29
Q

How can the magnification of an image

be calculated?

A

How can the magnification of an image be
calculated?

Magnification = Size of image/Size of specimen

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30
Q

What is resolution?

A

What is resolution?

The smallest distance between two distinct objects that can be distinguished

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31
Q

How does a light microscope work?

A

How does a light microscope work?

A light microscope passes a beam of light through a specimen. The light then travels through the eyepiece lens, allowing the specimen to be observed.

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32
Q

What are the advantages of light microscopes? (4)

A 
What are the advantages of light microscopes? (4)
● Inexpensive
● Easy to use
● Portable
● Observe both dead and living specimens
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33
Q

What is the disadvantage of light

microscopes?

A

What is the disadvantage of light microscopes?

Limited resolution

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34
Q

How does an electron microscope work?

A

How does an electron microscope work?

It uses a beam of electrons focused using magnets. The electrons hit a fluorescent screen which emits visible light, producing an image.

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35
Q

Name the two types of electron microscopes

A

Name the two types of electron microscopes

Transmission electron microscope (TEM)
Scanning electron microscope (SEM)

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36
Q

What is the advantage of electron

microscopes?

A

What is the advantage of electron microscopes?

Greater magnification and resolution

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37
Q

Why do electron microscopes have a

greater magnification and resolution?

A

Why do electron microscopes have a greater
magnification and resolution?

They use a beam of electrons which has a shorter wavelength than photons of light

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38
Q

How have electron microscopes enabled
scientists to develop their understanding
of cells?

A

How have electron microscopes enabled scientists
to develop their understanding of cells?
● Allow small sub-cellular structures (e.g. mitochondria, ribosomes) to be observed in detail
● Enable scientists to develop more accurate
explanations about how cell structure relates to function

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39
Q

What are the disadvantages of electron

microscopes? (4)

A 
What are the disadvantages of electron 
microscopes? (4)
● Expensive
● Large so less portable
● Require training to use
● Only dead specimens can be observed
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40
Q

How do you convert from m to mm?

A

How do you convert from m to mm?

× 1000 (× 10^3)

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41
Q

How do you convert from m to µm?

A

How do you convert from m to µm?

× 1 000 000 (× 10^6)

42
Q

How do you convert from m to nm?

A

How do you convert from m to nm?

× 1 000 000 000 (× 10^9)

43
Q

How do you convert from m to pm?

A

× 1 000 000 000 000 (× 10^12)

44
Q

What is the cell cycle?

A

What is the cell cycle?
● A series of events that take place in a cell
involving cell growth, DNA replication and
cell division
● It is described as the lifecycle of a cell

45
Q

State the two stages of the cell cycle

A

State the two stages of the cell cycle
Stage 1 - interphase
Stage 2 - mitosis

46
Q

What is interphase?

A

What is interphase?

The longest stage of the cell cycle that involves cell growth, the synthesis of new organelles and DNA replication

47
Q

What does DNA replication involve?

A

What does DNA replication involve?
● Double helix ‘unzips’ exposing two strands
● DNA bases align next to complementary bases on
the DNA strands
● Complementary base pairs join
● Two identical DNA molecules formed

48
Q

What is mitosis?

A

What is mitosis?

A form of cell division that produces two genetically identical ‘daughter’ cells with the same number of chromosomes

49
Q

Why is mitosis important in organisms?

A 
Why is mitosis important in organisms?
Mitosis is important for:
● Asexual reproduction
● Growth
● Repair of damaged cells
● Cell replacement
50
Q

Describe the stages of mitosis

A

Describe the stages of mitosis
● Chromosomes line up along the cell equator
● Spindle fibres pull the two arms of each chromosome to
opposite poles of the cell
● Nucleus of the cell divides
● A new membrane forms around each set of chromosomes
● Cell divides producing two identical daughter cells

51
Q

A cell divides by mitosis once every 2
minutes. Calculate the number of
identical cells present after 10 minutes.

A

A cell divides by mitosis once every 2 minutes.
Calculate the number of identical cells present after
10 minutes.

10 ÷ 2 = 5
5 cell divisions have taken place
2^5 = 32 cells

52
Q

What is cancer?

A

What is cancer?
● Non-communicable disease
● Uncontrolled cell division (due to damaged DNA) results
in the formation of a primary tumour
● Tumour cells break off and spread to other tissues
forming secondary tumours

53
Q

What is a non-communicable disease?

A

What is a non-communicable disease?

A disease that is not spread between organisms

54
Q

What is sexual reproduction?

A

What is sexual reproduction?
● Type of reproduction
● Involves the production of gametes by meiosis
● A gamete from each parent fuses to form a zygote
● Genetic information from each gamete is mixed so the resulting zygote is genetically different from each parent

55
Q

What are gametes?

A

What are gametes?
● Sex cells (sperm cells, egg cells)
● Contain half the chromosome number

56
Q

What is meiosis?

A

What is meiosis?
A form of cell division involved in the formation of gametes where chromosome number is halved. It involves two divisions.

57
Q

What must occur prior to meiosis?

A

What must occur prior to meiosis?

Interphase

58
Q

What happens during the first stage of

meiosis?

A

What happens during the first stage of meiosis?
The pair of chromosomes are separated and move to opposite poles of the cell.
Chromosome number is halved.

59
Q

What happens during the second stage

of meiosis?

A

What happens during the second stage of meiosis?
The arms of each chromosome are separated and move to opposite poles of the cell. Four genetically different gametes are produced.

60
Q

Why is meiosis important for sexual

reproduction? (2)

A

Why is meiosis important for sexual reproduction?
(2)
● It increases genetic variation
● It ensures that the resultant zygote has
a full set of chromosomes

61
Q

What are stem cells?

A

What are stem cells?
Cells that are unspecialised and capable
of differentiating into a range of different
cell types

62
Q

What is meant by ‘differentiation’?

A

What is meant by ‘differentiation’?
● A process in which stem cells become specialised
(have a specific function)
● Some genes switch on or off, determining cell
type

63
Q

Why is cell differentiation important?

A

Why is cell differentiation important?

It enables the formation of specialised tissues with specific functions e.g. muscle tissue.

64
Q

What are embryonic stem cells?

A

What are embryonic stem cells?

Stem cells found in very early embryos that are unspecialised and capable of differentiating into any cell type

65
Q

When do embryonic stem cells begin to

differentiate?

A

When do embryonic stem cells begin to
differentiate?
After the eight cell stage

66
Q

What is the function of embryonic stem

cells?

A

What is the function of embryonic stem cells?

They enable the growth and development of tissues in human embryos.

67
Q

What are adult stem cells?

A

What are adult stem cells?

Stem cells that can differentiate into a limited range of cell types e.g. bone marrow stem cells

68
Q

What is the primary function of adult

stem cells?

A

What is the primary function of adult stem cells?

Replacement of dead cells e.g. replacement of red blood cells which only live for 120 days

69
Q

Where are stem cells found in plants?

A

Where are stem cells found in plants?

Meristems

70
Q

Where is meristem tissue found?

A

Where is meristem tissue found?
In regions of the plant where cells are
continuously dividing e.g. root tips, shoot
tips

71
Q

What are meristematic stem cells?

A

What are meristematic stem cells?
Stem cells found in meristems that are unspecialised and capable of differentiating into any cell type during
the life of a plant

72
Q

What are plant tropisms?

A

What are plant tropisms?
The growth response of a plant to a
stimulus

73
Q

What is positive tropism?

A

What is positive tropism?

The growth of a plant towards a stimulus

74
Q

What is negative tropism?

A

What is negative tropism?
The growth of a plant away from a
stimulus

75
Q

What are the two main types of plant

tropism?

A

What are the two main types of plant tropism?
Phototropism
Gravitropism

76
Q

Define phototropism

A

Define phototropism

A plant’s growth response to light

77
Q

Define gravitropism

A

Define gravitropism

A plant’s growth response to gravity

78
Q

What are auxins?

A

What are auxins?
● A group of plant hormones involved in plant
tropisms
● Control growth in plant roots and shoot tips

79
Q

Compare the effect of auxins in plant

shoots and roots

A

Compare the effect of auxins in plant shoots and
roots
Auxins stimulate growth in plant shoots
Auxins inhibit growth in plant roots

80
Q

Where are auxins produced?

A

Where are auxins produced?

Root and shoot tips

81
Q

How do auxins move through a plant?

A

How do auxins move through a plant?

They diffuse through the plant in solution

82
Q

Are plant shoots positively or negatively
phototropic? How does this affect shoot
growth?

A

Are plant shoots positively or negatively phototropic?
How does this affect shoot growth?
● Positively phototropic
● Plant shoots grow towards the light

83
Q

Explain why plant shoots are positively

phototropic

A

Explain why plant shoots are positively phototropic
● Shoot tip exposed to light
● On the shaded side of the root, auxin accumulates
● Elongation of cells on the shaded side
● Shoot tip bends towards the light

84
Q

Are plant shoots positively or negatively
gravitropic? How does this affect shoot
growth?

A 
Are plant shoots positively or negatively gravitropic? 
How does this affect shoot growth?
● Negatively gravitropic
● Plant shoots grow upwards, away from 
gravity
85
Q

Explain why plant shoots are negatively

gravitropic

A

Explain why plant shoots are negatively gravitropic
● Shoot placed horizontally
● Due to gravity, auxin accumulates on the lower side of
the shoot
● Elongation of cells on the lower side
● Shoot bends upwards growing away from gravity

86
Q

Are plant roots positively or negatively
phototropic? How does this affect root
growth?

A

Are plant roots positively or negatively phototropic?
How does this affect root growth?
● Negatively phototropic
● Plant roots grow away from the light

87
Q

Explain why plant roots are negatively

phototropic

A

Explain why plant roots are negatively phototropic
● Root exposed to light
● On the shaded side of the root, auxin accumulates
● Inhibition of cell growth on the shaded side
● Root grows away from the light

88
Q

Are plant roots positively or negatively
gravitropic? How does this affect root
growth?

A 
Are plant roots positively or negatively gravitropic? 
How does this affect root growth?
● Positively gravitropic
● Plant roots grow downwards, towards 
gravity
89
Q

Explain why plant roots are positively

gravitropic

A

Explain why plant roots are positively gravitropic
● Root placed horizontally
● Due to gravity, auxin accumulates on the lower side of the root
● Inhibition of cell growth on the lower side
● Root bends downwards growing towards gravity

90
Q

Explain how plant tropisms increase the

chance of survival

A

Explain how plant tropisms increase the chance of
survival
● They enable plants to respond to their environment
● Shoot growth towards the light maximises light absorption
● Root growth downwards increases the uptake of water and minerals from the soil and enables anchorage of the plant body to the ground

91
Q

Describe the role of auxins in

commercial plant cultivation

A

Describe the role of auxins in commercial plant
cultivation
● Rooting powders contain auxins
● Auxins stimulate the growth of roots in cuttings
● Enables rapid plant cloning

92
Q

What are gibberellins?

A

What are gibberellins?
Plant hormones that control germination
and flowering

93
Q

How do gibberellins trigger germination?

A

How do gibberellins trigger germination?

In the presence of water, gibberellins break seed dormancy, initiating germination.

94
Q

What is ‘bolting’ in plants?

A

What is ‘bolting’ in plants?
● In response to a period of low temperatures or limited water availability
● Flowering and seed production increase in a final bid
for a plant to reproduce before death
● Triggered by gibberellins

95
Q

Why are gibberellins important in

commercial plant cultivation?

A

Why are gibberellins important in commercial plant
cultivation?
● Applied to seeds to make them germinate at times of the year when
they naturally wouldn’t
● Makes sure all seeds germinate at the same time
● Initiate flowering in plants at any time of the year
● Enable flowering under conditions in which plants would normally not
● Can increase fruit size

96
Q

What effect does ethene have on plants?

A

What effect does ethene have on plants?
● Causes dead leaves to drop off a plant by
triggering the expansion and bursting of cells in
leaf stalks
● Stimulates enzymes that control fruit ripening

97
Q

Why is ethene important in commercial

plant cultivation?

A

Why is ethene important in commercial plant
cultivation?
● Used to remove the dead leaves from plants, aiding
the collection of fruits and seeds
● Enables fruits to be picked while they are unripe and
less easily damaged. They can be stimulated to ripen
during transportation to shops.

98
Q

How can stem cells be used in

medicine?

A

How can stem cells be used in medicine?
● Stem cells collected
● Stem cells stimulated to differentiate into specific
cell types e.g. heart muscle cells
● Specialised cells transplanted into the patient
● Used to treat damage or disease e.g. heart disease

99
Q

Where can embryonic stem cells be

collected from? (2)

A 
Where can embryonic stem cells be collected from? 
(2)
● Donor stem cells removed from 
embryos grown in vitro
● Patient’s own stem cells removed from 
the umbilical blood before birth
100
Q

What are the benefits of using stem cells

in medicine? (4)

A

What are the benefits of using stem cells in
medicine? (4)
● Treat damage or disease e.g. heart disease, type 1 diabetes
● Treat diseases that would otherwise be untreatable
● Used in scientific research
● Growing organs for transplants

101
Q

What are the risks of stem cell use in

medicine? (6)

A

What are the risks of stem cell use in medicine? (6)
● Transplanted stem cells could cause tumours
● Finding suitable stem cell donors is a difficult task
● Stem cells may be rejected by the body (immunosuppressants taken)
● Potential side effects
● Long term risks of using stem cells are unknown
● Stem cells may become contaminated during preparation and when
transplanted, transmit infections to the patient, making them sicker

102
Q

What are the ethical issues related to the

use of stem cells in medicine? (2)

A

What are the ethical issues related to the use of
stem cells in medicine? (2)
● The embryos used to provide stem cells are
destroyed which is seen as unethical and a waste
of potential human life
● May lead to the reproductive cloning of humans

Biology Flashcards - OCR 21st Century (11 decks)

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