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Biology AQA Triple > Cell Biology > Flashcards

Cell Biology Flashcards

Paper 1 - B1

1
Q

What type of organisms are prokaryotic
cells?

A

Bacteria

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2
Q

What type of organisms have eukaryotic
cells?

A

Plants and animals (& fungi)

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3
Q

What is the function (job) of the nucleus in a cell?

A

To control the cell. Contains DNA.

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4
Q

What is the function (job) of the cell
membrane?

A

To control what substances can enter or leave the cell

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5
Q

What is the function of the mitochondria?

A

To release energy in respiration

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6
Q

What process takes place at the
ribosomes?

A

Protein synthesis / making proteins

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7
Q

What is the role of chloroplasts?

A

Absorb sunlight for photosynthesis. Contains chlorophyll

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8
Q

What is inside the permanent vacuole of a plant cell?

A

Cell sap

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9
Q

Name three cell parts (organelles) found in plant cells but not animal cells

A

Cell wall, permanent vacuole, chloroplasts

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10
Q

Name one structure you might find in the cytoplasm of a prokaryotic cell but not in a eukaryotic cell

A

DNA or plasmid

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11
Q

Name one structure found in eukaryotic
cells but not prokaryotic cells

A

A nucleus surrounding the genetic material (or accept mitochondria)

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12
Q

Which are the smallest, prokaryotic or
eukaryotic cells?

A

Prokaryotic cells are much smaller

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13
Q

What is the cell wall made of in plant and algal cells?

A

Cellulose

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14
Q

What are the adaptations of a sperm cell?

A

Flagella to swim towards the egg, acrosome to digest egg cell membrane, lots of mitochondria to supply energy for swimming, haploid nucleus

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15
Q

What are the adaptations of a nerve cell?

A

Long axon to transmit nerve impulses,
branched nerve endings/dendrites to
send/receive impulses from other neurones, fatty sheath/insulating layer to speed up nerve impulses

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16
Q

What are the adaptations of a muscle cell?

A

Proteins filaments that slide to cause muscle contraction, lots of mitochondria to release energy, many nuclei because cells have merged to form a stronger structure

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17
Q

What are the adaptations of a root hair cell?

A

Long projection of the cell membrane to increase surface area for water to move in

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18
Q

What are the adaptations of xylem cells?

A

Dead hollow cells to form a tube for water transport; thickened with lignin

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19
Q

What are the adaptations of phloem cells?

A

Perforated end walls to act as a sieve for sugar solution to pass through

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20
Q

What is cell ‘differentiation’?

A

The process of cells becoming specialised by acquiring different sub-cellular structures to enable it to carry out a certain function

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21
Q

What are the reasons why cell division is necessary in mature animals?

A

For repair (of tissues) and replacement (of damaged cells), NOT “repair of cells”

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22
Q

How have developments in microscopy allowed us to understand more about subcellular structures such as ribosomes and mitochondria?

A

We have electron microscopes which have a much higher magnification and resolution, so can see finer details inside cells.

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23
Q

State two advantages of an electron
microscope over a light microscope.

A

Higher magnification, greater resolving power (resolution)

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24
Q

What is the formula for magnification?

A

Magnification = size of image / size of real
object

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25
Q

(Triple only) How do bacteria divide?

A

By binary fission

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26
Q

(Triple only) How often do bacteria divide?

A

Once every 20 minutes if they have enough nutrients and a suitable temperature

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27
Q

(Triple only) Name two types of growth
medium for bacteria

A

Agar gel plate or nutrient broth solution

28
Q

(Triple only) What is the purpose of aseptic technique?

A

To prepare an uncontaminated culture of
microorganisms

29
Q

(Triple only) In aseptic technique, why must petri dishes and culture media be sterilised before use?

A

To kill any bacteria or other microorganisms that could multiply and contaminate the experiment

30
Q

(Triple only) In aseptic technique, how can inoculating loops be sterilised?

A

By passing through a Bunsen flame

31
Q

(Triple only) In aseptic technique, why are Petri dishes stored upside down?

A

To prevent condensation affecting bacterial growth

32
Q

(Triple only) When growing bacteria in a school laboratories, why are cultures generally incubated at temperatures no higher than 25 degrees Celsius?

A

To prevent the growth of microorganisms that are harmful to humans (which are likely to
multiply at temperatures close to body temperature)

33
Q

(Triple only) What formula would you use to calculate the cross-sectional area of a bacterial colony or the clear area around it?

A

πr²

34
Q

What is found in the nucleus of cells?

A

Chromosomes made of DNA molecules

35
Q

During the cell cycle, what happens to the genetic material (DNA) before mitosis?

A

It replicates (doubles)

36
Q

During the cell cycle, aside from the
doubling (replication) of the DNA, what else happens within the cell?

A

The cell grows and increases the number of sub-cellular structures (organelles) e.g. ribosomes, mitochondria

37
Q

What happens to the chromosomes during mitosis?

A

They are pulled to opposite ends of the cell

38
Q

What happens to the nucleus of a cell at
the end of mitosis?

A

It divides

39
Q

What happens to the cytoplasm and cell
membranes at the end of mitosis?

A

They divide to form two identical cells

40
Q

Why is cell division by mitosis important in
multicellular organisms?

A

For growth and development

41
Q

What is a stem cell?

A

An undifferentiated cell of an organism,
capable of giving rise to many more cells of the
same type and from which certain other cells
can arise from differentiation.

42
Q

What is the function of stem cells in
embryos?

A

To allow the embryo to grow and produce specialised cells to develop into tissues and organs

43
Q

Where are stem cells found in adult
humans, which can develop into many
types of cells including blood cells?

A

Bone marrow

44
Q

Name the tissue in plants where stem cells
are found

A

Meristem

45
Q

Why are stem cells useful to treat diseases?

A

They can be cloned and made to differentiate into most different types of human cells

46
Q

Name the process by which an embryo is produced with the same genes as the patient so that stem cells can be removed and used to treat diseases

A

Therapeutic cloning

47
Q

Give one risk of using stem cells to treat
diseases

A

Possible transfer of viral infection

48
Q

Give one reason why people might object
to stem cell use for ethical or religious
reasons

A

Because an embryo is killed, which is a
potential life

49
Q

Give one reason why plant growers might
want to use stem cells to produce clones of
plants

A

To prevent rare species from extinction; to
produce large numbers of identical plants with
specfiic features e.g. disease resistance

50
Q

What is diffusion?

A

Spreading out of particles resulting in net
movement from an area of higher
concentration to an area of low concentration

51
Q

Name two substances transported into and
out of cells by diffusion

A

oxygen and carbon dioxide

52
Q

Name the waste product that diffuses out
of cells into blood plasma for excretion in
the kidney

A

urea

53
Q

Name three factors that affect the rate of
diffusion

A

Difference in concentrations; temperature; surface area of membrane

54
Q

Does a single-celled organism have a
relatively large or small surface area to
volume ratio compared to larger animals?

A

Large

55
Q

Why can a single-celled organism rely on
diffusion to meet it’s needs (e.g. of oxygen)
but a larger animal requires exchange
surfaces and a transport system?

A

Because it has a larger surface ara to volume
ratio.

56
Q

Name the gas exchange surface in fish

A

Gills

57
Q

What are the ways in which the small intestine is
adapted for diffusion of small food
molecules into the blood?

A

Villi to increase the surface area; good blood
supply to maintain concentration gradient;
thin walls

58
Q

What are the ways in which the lungs in
mammals are adapted for diffusion of
oxygen into the blood and carbon dioxide
back out?

A

Alveoli to increase surface area; walls are 1 cell
thick; lots of capillaries to maintain
concentration gradient

59
Q

What are the ways in which the gills of fish are
adapted for diffusion of oxygen into the
blood and carbon dioxide back into the
water?

A

Layered structure (filaments, lamellae) to
increase the surface area; very thin

60
Q

What are the ways in which all exchange surfaces (e.g. the lungs) are adapted for efficient diffusion

A

large surface area; efficient blood supply; thin
membrane (short diffusion path); ventiliated
(to maintain concentration gradient)

61
Q

What is osmosis?

A

Diffusion of water from a dilute solution to a
concentrated solution through a partially
permeable membrane

62
Q

What is active transport?

A

Movement of substances from a more dilute
solution to a more concentrated solution
(against concentration gradient). Requires
energy from respiration.

63
Q

What is required for active transport which
is not required for diffusion?

A

Energy from respiration (released in
mitochondria)

64
Q

Which organelle (cell part) might be more
common in a cell carrying out active
transport?

A

Mitochondria

65
Q

Why do root hair cells need a supply of
oxygen?

A

For respiration and to provide energy for active
transport to take up minerals.

66
Q

Give an example of active transport in
plants

A

Taking up mineral ions from the soil via root
hair cells from very dilute solutions

67
Q

Give an example of active transport in
animals

A

Absorbing sugar from low concentrations in
the gut into the blood which has a higher sugar
concentration

Biology AQA Triple (16 decks)

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