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Biology GCSE > cell structure > Flashcards

cell structure Flashcards

1
Q

Where is the genetic material in a prokaryotic cell?

A

In a bacterial DNA loop and there may be one or more plasmid rings.

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2
Q

Where is the genetic material in a eukaryotic cell?

A

The DNA is in chromosomes enclosed in a nucleus.

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3
Q

Why do scientists use prefixes?

A

To make very small numbers more manageable

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4
Q

sperm functions and features

A

function is to fertilise an egg.

  • streamline with long tail to swim faster
  • acrosome in head to digest egg cell membrane
  • large number of mitochondria to release energy for swimming
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5
Q

nerve functions and features

A

function is to carry electric signals

-long to carry signals long distances
-branched connections to connect with other nerve cells and form a network around the body
insulating sheath to enhance transmissions of electric signals

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6
Q

muscle functions and features

A

function is to contract to allow movement

  • contain a large number of mitochondria to release energy from respiration for movement
  • long so that there is enough space to contract
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7
Q

root hair functions and features

A

function is to absorb water and minerals from the soil

-hair like projections to increase the surface area

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8
Q

xylem functions and features

A

function is to carry water and minerals in plants

  • form hollow xylem tubes made of dead tissue
  • cells have end plates with holes in them
  • glucose in solution moves from leaves to growth and storage tissues in a process called TRANSLOCATION
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9
Q

cytoplasm

A

where chemical reactions happen

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10
Q

motchondria

A

most energy is released by respiration here

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11
Q

ribosomes

A

protein synthesis happens here

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12
Q

vacuole

A

filled with sap to make cell stronger

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13
Q

plasmid

A

small ring of dna used in genetic modification

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14
Q

What does cell differentiation mean?

A

When a cell changes to become specialised.

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15
Q

In what stage of an animal’s life cycle do most cells differentiate?

A

early stages

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16
Q

In mature animals when do cells still need to differentiate?

A

for replacement and repair of cells

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17
Q

In what stage of their life cycle do plant cells differentiate?

A

they differentiate throughout

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18
Q

Define the term resolution.

A

The shortest distance between two objects that can be seen clearly.

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19
Q

What are the advantages of the electron microscope?

A

Electron microscopes

have a higher magnification and resolution than light microscopes

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20
Q

Name the smallest cell structures that can be seen by the light microscope?

A

Nuclei and mitochondria

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21
Q

What are the smallest cell structures that can be seen by the electron
microscope?

A

internal structures of mitochondria and chloroplasts.

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22
Q

magnification equation

A

magnification = size of image/size of real object

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23
Q

Describe how you would make an onion cell slide.

A

-Place thin section of onion epidermis onto slide.
-Place a drop of iodine in the middle of the slide to stain the onion.
-Gently lower cover slip onto the onion without trapping air
bubbles.
-Soak up any excess liquid with a paper towel.

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24
Q

Describe how you would use the light microscope to view onion
cells.

A

-Switch on the light source and place your slide on the stage.
-Use the lowest objective lens and turn the focusing wheel to move
the lens close to the slide.
-Slowly adjust the focusing wheel until you can see a clear image.
-Increase the magnification by changing the objective lens and re-focus.

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25
Q

What is ‘binary fission’?

A

Cell division where two identical cells to the

parent cell are formed.

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26
Q

Why do you need to sterilise Petri dishes and culture mediums before
use?

A

To kill any unwanted microorganisms.

27
Q

What would you use an inoculating loop for?

A

To transfer bacteria onto

the agar.

28
Q

How do you sterilise an inoculating loop?

A

By heating in a Bunsen flame.

29
Q

How would you secure the lid of the Petri dish?

A

With tape but not sealed

all the way around.

30
Q

What temperature would you incubate the samples at in a school and why should you use this temperature?

A

25oC, to prevent the growth of pathogens harmful to humans.

31
Q

How can you test the effectiveness of antibiotics and disinfectants on
bacteria?

A

Inoculate agar with bacteria, place discs soaked in the solutions
(water as a control) and place the discs on the agar containing bacteria.
Incubate at 25oC.

32
Q

What is the zone of inhibition?

A

An area where bacteria don’t grow.

33
Q

What are chromosomes?

A

Coiled strands of DNA molecules.

34
Q

what is a gene?

A

a section of dna that codes for a protien

35
Q

What is DNA?

A

A genetic material found in the nucleus that codes for proteins.

36
Q

Where in a cell do you find chromosomes?

A

In the nucleus of cells.

37
Q

How many chromosome pairs do you find in a human body cell?

A

23

38
Q

What are the three stages of the cell cycle?

A

Growth, DNA synthesis and mitosis.

39
Q

What is mitosis and what is it used for in animals and plants?

A

Growth, repair and asexual reproduction.

40
Q

what is a stem cell

A

a cell that is undifferentiated

41
Q

Which type of human stem cell can differentiate into any human
cell?

A

embryo stem cells

42
Q

What is therapeutic cloning?

A

Where patients are given stem cells

containing the same genes as theirs.

43
Q

What are the risks of therapeutic cloning?

A

Viral infections.

44
Q

State two reasons why people may object to the use of stem cells
in therapeutic cloning.

A

Ethical and religious reasons.

45
Q

What are meristems?

A

Structures in plants that contain stem cells.

46
Q

State two reasons that plants are cloned?

A

To clone rare species of

plants and to clone crop plants with useful characteristics.

47
Q

Define ‘diffusion’?

A

The spreading of the particles from a region where they are of a
higher concentration to an area of lower concentration.

48
Q

State three places where diffusion occurs in the body.

A

Small intestines, lungs, kidneys

49
Q

What is a concentration gradient?

A

The difference in concentration

between two areas next to each other.

50
Q

What three factors affect rate of diffusion?

A

Concentration gradient,

temperature, surface area.

51
Q

What is surface area to volume ratio?

A

The size of a surface

compared to its volume.

52
Q

Which has the largest surface area to volume ratio an elephant or a
meerkat?

A

The meerkat.

53
Q

how the small intestines are adapted for diffusion

A

Have villi to increase surface area, good

blood supply, thin membranes.

54
Q

how the lungs are adapted for diffusion

A

Have alveoli to increase surface area, good blood supply, thin membranes, they are ventilated.

55
Q

how gills in fish are adapted for diffusion

A

Have gill filaments and lamella to increase surface

area, good blood supply, thin membranes.

56
Q

how roots are adapted for diffusion

A

Have root hair cells to increase surface area.

57
Q

how leaves are adapted for diffusion

A

Large surface area, thin and stomata.

58
Q

Define osmosis?

A

Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

59
Q

What is a partially permeable membrane?

A

A membrane that lets

some but not all substances through.

60
Q

What happens to an animal cell in a hypertonic solution?

A

It will lose water by osmosis and shrivel.

61
Q

What happens to an animal cell in a hypotonic solution?

A

It will absorb water by osmosis and get bigger/burst.

62
Q

Define active transport.

A

Active transport moves substances from a
more dilute solution to a more concentrated solution (against a
concentration gradient) using energy from respiration.

63
Q

Why does active transport need to occur in root hair cells?

A

Because the minerals are at a higher concentration in the roots than in the soil.

64
Q

Why does active transport need to occur in the gut?

A

Because the glucose in the blood is at a higher concentration than in the gut.

Biology GCSE (6 decks)

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