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Biology 9-1 iGCSE Oxford AQA > Cell Biology > Flashcards

Cell Biology Flashcards

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1
Q

What are eukaryotic cells like and where are they found?

A
  • Are complex (include all animal and plant cells)

- Organism made up of eukaryotic cells

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2
Q

What are prokaryotic cells like and where are they found?

A
  • Prokaryotic cells are smaller and simpler e.g. Bacteria

- Are single-celled organism

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3
Q

Name 5 features of an animal cell

A
  • Nucleus
  • Mitochondria
  • Cytoplasm
  • Cell membrane
  • Ribosomes
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4
Q

What’s the function of nucleus?

A

Contains genetic material that controls activities of cell

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5
Q

What’s the function of mitochondria?

A

Where most of the reactions for aerobic respiration take place (respiration transfers energy that the cell needs to work)

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6
Q

What’s the function of cytoplasm?

A

Where most of the chemical reactions happen - contains enzymes that control these chemical reactions

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7
Q

What is the cytoplasm?

A

Gel-like substance

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8
Q

What’s the function of a cell membrane?

A

Holds cell together and controls what goes in and out

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9
Q

What’s the function of ribosomes?

A

Where proteins are made in the cell (where protein synthesis occurs)

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10
Q

What 3 features do plants cells have but not animals cells?

A
  • Cell wall
  • Chloroplasts
  • Permanent vacuole
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11
Q

What’s the function of chloroplasts?

A

Where photosynthesis occurs which makes food for plant

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12
Q

What does chloroplasts contain and why?

A

Contain a green substance called chlorophyll which absorbs light needed for photosynthesis

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13
Q

What is the cell wall made out of (in a plant)?

A

Made of cellulose

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14
Q

What’s the function of a cell wall?

A

Supports the cell and strengthens it

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15
Q

What’s the function of a permanent vacuole?

A
  • Contains cell sap (weak solution of sugar and salts)

- Keeps the cell rigid to support plant

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16
Q

What do bacterial cells have instead of nucleus?

A

Have a single circular strand of DNA that floats freely in

cytoplasm

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17
Q

What are plasmids and where are they found?

A

Small rings of DNA found in bacterial cells

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18
Q

Do bacterial cells have chloroplasts or mitochondria?

A

No

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19
Q

What is cell differentiation?

A

The process by which a cell changes to become specialised for its job

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20
Q

Explain briefly how cells differentiate

A

As cell change, they develop different subcellular structures = turn into different types of cells

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21
Q

When does most cell differentiation occur?

A

Occurs as an organism develops

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22
Q

When do animals cells lose the ability to differentiate?

A

Most animal cells lose the ability to differentiate at an early stage, after they become specialised

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23
Q

Do plant cells lose the ability of differentiate?

A

Lots of plant cells don’t ever lose the ability

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24
Q

What are cells that differentiate in mature animals used for mainly?

A

Mainly used for repairing and replacing cells (skin, blood cells)

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25
Q

What are sperm cells specialised for?

A

Specialised for reproduction

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26
Q

What is the function of a sperm cell?

A

To get male DNA to female DNA

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27
Q

Name 3 ways a sperm cell is specialised for its job

A
  • Lot of mitochondria to provide energy needed (via respiration)
  • Long tail and streamlined head to help it swim to egg
  • Carries enzymes in head to digest through egg cell membrane
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28
Q

What are nerve cells specialised for?

A

Rapid signalling

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29
Q

What is the function of a nerve cell?

A

To carry electrical signals from one part of body to another

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30
Q

Name 2 ways a nerve cell is specialised for its job

A
  • Are long (to cover more distance)

- Have branched connections at their ends to connect to other nerve cells to form a network throughout body

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31
Q

What are muscle cells specialised for?

A

Contraction

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32
Q

What is function of a muscle cell?

A

To contact quickly

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33
Q

Name 2 ways a muscle cell is specialised for its job

A
  • Long so they have space to contract

- Contains lots of mitochondria to generate energy needed for contraction

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34
Q

What are root hair cells specialised for?

A

Absorbing water and minerals

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35
Q

Name a way a root hair cell is specialised for its job

A
  • Grow long ‘hairs’ that stick out into soil = gives the plant a big surface area for absorbing water and mineral ions from soil
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36
Q

Name 3 animal tissues

A
  • Muscular Tissue
  • Glandular Tissue
  • Epithelial Tissue
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37
Q

What does the muscular tissue do?

A

Contracts (shortens) to move whatever it’s attached to

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38
Q

What does the glandular tissue do?

A

Makes and secretes chemicals like enzymes and hormones

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39
Q

What does the epithelial tissue do?

A

Covers whole surface of body and some parts of body

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40
Q

In the stomach, describe what the 3 main tissues do

A
  • Muscular tissue moves the stomach wall to churn food
  • Glandular tissue makes digestive juices to digest food
  • Epithelial tissue covers the outside and inside of stomach
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41
Q

Name the four main tissues in plants

A
  • Epidermal Tissue
  • Palisade Mesophyll Tissue
  • Spongy Mesophyll Tissue
  • Xylem and Phloem
42
Q

What does the epidermal tissue do?

A

Covers whole plant

43
Q

What are epidermal tissues covered in and why?

A

Covered in waxy cuticle, helps reduce water loss by evaporation

44
Q

Name a feature (and its purpose) of the upper epidermal tissue

A

Is transparent so light can pass through to palisade layer

45
Q

Name a feature (and its purpose) of the lower epidermal tissue

A

Full of holes (stomata) to increase gas exchange (carbon dioxide diffuse in and oxygen diffuse out)

46
Q

What does the palisade mesophyll tissue contain?

A

Lots of chloroplasts

47
Q

What happens in the palisade mesophyll tissue?

A

Where most of photosynthesis happens

48
Q

Name a feature (and its purpose) of the palisade mesophyll tissue

A

Near top of leaf so it can get most light

49
Q

Name a feature (and its purposes) of the spongy mesophyll tissue

A

Big air spaces to allow carbon dioxide to diffuse through leaf (gases to diffuse in and out of cells) & increase surface area

50
Q

What does the tissues xylem and phloem do?

A

Help support structure

51
Q

What are the xylem and phloem?

A

Network of vascular bundles which deliver water and other nutrients to entire leaf & take away glucose produced by photosynthesis

52
Q

Define diffusion

A

Diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration

53
Q

How can you increase the rate of diffusion (name 2 way)?

A
  1. Bigger the concentration of gradient (different in concentration) = faster the diffusion rate
  2. Higher temperature = faster rate of diffusion because particles have more energy to move around faster
54
Q

Define osmosis

A

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

55
Q

What is a partially permeable membrane?

A

Membrane with very small holes in it

56
Q

What does partially permeable membrane let through?

A

Only allows tiny molecules (like water) can pass through them and bigger molecules (sucrose) can’t

57
Q

What does it mean if a solution is isotonic?

A

Solute concentration of solution is SAME as solute concentration inside cell

58
Q

What does it mean if a solution is hypertonic?

A

Solute concentration of solution is HIGHER than solute concentration inside cell

59
Q

What does it mean if a solution is hypotonic?

A

Solute concentration of solution is LOWER than solute concentration inside cell

60
Q

What is active transport?

A

When substances are absorbed against a concentration gradient (low to high). This requires the use of energy from respiration.

61
Q

What does active transport allow plants to?

A

Active transport allows plant to absorb minerals form a very dilute solution, against a concentration gradient (but NEEDS ENERGY from respiration)

62
Q

Explain how active transport stops us from starving?

A
  1. SOMETIMES there’s a lower concentration of nutrients in gut than in blood
  2. Active transport is used to allow nutrients to be taken into the blood - despite the fact concentration gradient is the wrong way
63
Q

Name and explain 4 ways that exchange surfaces are adapted to maximise effectiveness (i.e. ways they speed up diffusion)

A
  1. Thin membrane - short distance to diffuse
  2. Large surface area - lots of a substance can diffuse at once
  3. Efficient blood supply (lots of blood vessels) (in animals) - maintains the concentration gradient
  4. Gas exchange surfaces often ventilated (animals) - supplies more O2 and keeps concentration difference high
64
Q

What are villi and where are they found?

A

Tiny little projections (millions of them) that cover the inside small intestine

65
Q

How does villi help absorption in the small intestine?

A

They increase surface area so digested food is absorbed much more quickly into the blood

66
Q

What 2 features do villi that speeds up diffusion (excluding large surface area)?

A
  • Very good blood supply to assist quick absorption

- Have single layer of surface cells

67
Q

Name 5 adaptations of alveoli

A
  • Good blood supply
  • Very thin walls (lining only one cell thick)
  • Ventilation (breathing) - steep concentration gradient
  • Moist lining for dissolving gases
  • Are folded = massive surface area
68
Q

Explain how the shape of leaf makes it a good exchange surface

A

Flattened shape of leaf increases surface area of exchange surface = more effective

69
Q

Explain how the underneath of a leaf is a good exchange surface

A

Covered in stomata = carbon dioxide diffuse in & oxygen and water vapour diffuse out

70
Q

What is the size of stomata controlled by?

A

Guard cells

71
Q

What do guard cells do (to help with gas exchange)?

A

Close the stomata if plant is losing water faster than it is being replaced by roots

72
Q

What would happen if a plant didn’t have guard cells?

A

Without guard cells, plant would wilt

73
Q

Explain how the walls of cells inside leaf forms another exchange surface

A

Air spaces inside leaf increase the area of this surface so there’s more chance for carbon dioxide to get into cells

74
Q

What are phloem and xylem cells specialised for?

A

Specialised for transporting substances

75
Q

What feature do phloem and xylem cells have that makes them suited for their job?

A

Xylem cells are hollow in centre and phloem have very few subcellular structures - so stuff can flow through them

76
Q

What do phloem and xylem cells form?

A

Form phloem and xylem tubes which transport substances (food, water) around plant

77
Q

What are stem cells?

A

Undifferentiated cells that can become `any type of cell

78
Q

What can we do with stem cells?

A

Can be grown in labs to produce clones & made to differentiate into specialised cells - to use in medicine or
research

79
Q

Where are stem cells found mostly?

A

Early human embryos & umbilical cord of newborn babies

80
Q

Where are stem cells found in adults?

A

Liver and bone marrow

81
Q

Why aren’t stem cells found adults as useful as embryonic stem cells?

A

But they can’t turn into any type of cell - only certain ones
e.g. blood cells

82
Q

How can we use adult stem cells to cure diseases (in medicine)?

A

Stem cells can be transferred from bone marrow of healthy person can replace faulty blood cells

83
Q

What can we use embryonic stem cells for?

A

They be used to replace faulty cells in sick people e.g. nerve cells for spinal injuries

84
Q

What is therapeutic cloning?

A

When an is embryo made to have same genetic info as a patient

85
Q

What is the benefit of therapeutic cloning?

A

Stem cells produced have same genes so they wouldn’t be rejected

86
Q

Name 3 arguments against stem cell research

A
  • Human embryos have potential human life
  • Scientist should concentrate on finding and developing other sources of stem cells
  • People can be helped without embryos
87
Q

Name 2 arguments for stem cell research

A
  • Curing patients who already exist & are suffering = more important than rights of embryos
  • Embryos used are unwanted ones from fertility clinics - if weren’t used for research, would be destroyed
88
Q

Where are stem cells found in plants?

A

Found in meristems (where growth occurs in plants) = in most parts of the plant

89
Q

What are stem cells used for (plant wise)?

A

Used to produce clones of whole plants quickly and cheaply

90
Q

What can stem cells be used for grow (plant wise - give two ideas)?

A
  • Crops of identical plants - have desired features for farmers e.g. disease resistance
  • More plants of rare species (prevent extinction)
91
Q

What happens when you put a plant cell in a hypotonic solution?

A

Makes plant stiff - it becomes turgid (normal)

92
Q

What happens when you put a plant cell in a isotonic solution?

A

It will become flaccid - it’ll wilt (become floppy)

93
Q

What happens when you put a plant cell in a hypertonic solution?

A

It will become plasmolysed (causes irreversible damage)

94
Q

What happens when you put a red blood cell in a hypotonic solution and why?

A

It will become lysed - bursts because it doesn’t have a cell wall

95
Q

What happens when you put a red blood cell in a isotonic solution?

A

It’ll be normal - nothing

96
Q

What happens when you put a red blood cell in a hypertonic solution?

A

It will be shrivelled

97
Q

Marram grass have rolled leaves and live in dry and hot conditions, explain how this helps them to survive

A

Water is trapped inside = no concentration gradient

98
Q

Why don’t single celled organisms require complex structures for gas exchange? Two reasons

A
  • Large SA to Volume Ratio

- Short Diffusion Distance

99
Q

Why doesn’t algae require complex structures for gas exchange? One reason

A

Flow of water maintains concentration gradient

100
Q

What increases a leaf’s surface area to volume ratio?

A

Flattened shape and internal air spaces

101
Q

Name one feature of a yeast cell

A

Has vacuole

102
Q

What is meant by plasmolysed?

A

Cell membrane moves away from cell wall

Biology 9-1 iGCSE Oxford AQA (11 decks)

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