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AQA Biology > B1 Biology > Flashcards

B1 Biology Flashcards

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1
Q

List 5 features found in an animal cell

A

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

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2
Q

Explain the function of the nucleus

A

Nucleus: Contains the genetic information which controls cell activities

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3
Q

Explain the function of the cytoplasm

A

Cytoplasm: Gel-like substance where most chemical reactions take place

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4
Q

Explain the function of the cell membrane

A

Cell membrane: Holds cell together, controls what goes in and out of the cell

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5
Q

Explain the function of the mithochondria

A

Mitochondria: Structures in cytoplasm where aerobic respiration takes place, releasing energy for the cell

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6
Q

Explain the function of ribosomes

A

Ribosomes: Where protein synthesis takes place

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7
Q

List 3 additional features found in a plant cell

A

Cellulose cell wall, chloroplasts, permanent vacuole

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8
Q

Explain the function of the cellulose cell wall

A

Cellulose cell wall: Strengthens cell and gives it support

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9
Q

Explain the function of the chloroplasts

A

Chloroplasts: Where photosynthesis occurs. Contains a green pigment called chlorophyll which absorbs light for photosynthesis

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10
Q

Explain the function of the permanent vacuole

A

Permanent vacuole: Cell sap which keeps the cell rigid to support the plant

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11
Q

List 3 things found in a eukaryotic cell

A

Cell membrance
Cytoplasm
Genetic material (enclosed in a nucleus)

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12
Q

How does the genetic material found in a eukaryotic cell differ from the genetic material found in a prokaryotic cell?

A

Eukaryotic cell: DNA is enclosed in a nucleus

Prokaryotic cell: DNA is found as a single loop found free in cytoplasm

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13
Q

List 3 additional features found in prokaryotic cells

A

Plasmids
Protective slime capsule
Flagella

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14
Q

Explain the function of plasmids

A

Plasmids: Code for specific features (such as antibiotic resistance)

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15
Q

Explain the function of the protective slime capsule

A

Protective slime capsule: Used for protection

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16
Q

Explain the function of the flagella

A

Flagella: Protein strand used for movement

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17
Q

What are nerve cells specialised to do?

A

Rapid signalling: to carry electrical impulses around the body of an animal

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18
Q

Explain 4 ways nerve cells are adapted to carry out their function

A
  • Lots of dendrites: make connections to other nerve cells
  • Long axon: Carries impulse from place to another
  • Fatty myelin sheath: Insulates the nerve cell, speeding up the nerve impluse
  • Synapses contain mitochondria: Provide energy needed to make transmitter chemicals
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19
Q

What do transmitter chemicals do (nerve cells)?

A

Help the synapses to pass impulses to other cells

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20
Q

What are muscle cells specialised to do?

A

Contraction: relax and contract in pairs to move bones

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21
Q

Explain 4 ways muscle cells are adapted to carry out their function

A
  • Contain special protein which slide over each other, making the fibres contract
  • Many mitochondria: Transfer energy needed for the chemical reactions that happen
  • Long: Space to contract
  • Can store a chemical called glyogen which can be used in cellular respiration by mitochondria, to transfer energy for the fibres to contract
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22
Q

What are sperm cells specialised for?

A

Reproduction

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23
Q

Explain 4 ways sperm cells are adapted to carry out their function

A
  • Long tail: Helps sperm move
  • Middle section contains mitochondria which transfers the energy for the tail to work
  • Acrosome contains digestive enzymes: Break down the outer layers of the egg
  • Large nucleus: Contains the genetic information
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24
Q

What are root hair cells specialised for?

A

Absorbing water and minerals

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25
Q

Explain 3 ways root hair cells are adapted to carry out their function

A
  • Can greatly increase surface area: More water can move into cell
  • Large permanent vacuole: Speeds up the movement of water from the soil to the root hair cell by osmosis
  • Many mitochondria: Transfers the energy needed for the active transport of mineral ions into the cell
26
Q

What are xylem cells specialised for?

A

Carrying water and mineral ions from the roots to the highest leaves and the shoots

27
Q

Explain 2 ways xylem hair cells are adapted to carry out their function

A
  • Alive when first formed; chemical called lignin builds up in the cell walls, causing the cells to die and form long hollow tubes which allow the water and mineral ions to move up
  • Spirals of lignin makes cells strong and helps them withstand the pressure of water moving up the plant
28
Q

What are phloem cells specialised for?

A

Carrying the food, made by photosynthesis, around the body of the plant

29
Q

Explain 2 ways phloem hair cells are adapted to carry out their function

A
  • Cell walls die to form special sieve plates which allows water, carrying dissolved food, to move up the plant
  • Loses its internal structures but are suported by companion cells which transfer the energy needed for the food to move up the plant
30
Q

What are photosynthetic cells specialised for?

A

Allowing plants to make their own food

31
Q

Explain 3 ways phloem hair cells are adapted to carry out their function

A
  • Chloroplasts: Contain chlorophyll which absorbs light for photosynthesis
  • Positioned in outer layers of plant’s stem so that the cell can absorb as much light as possible
  • Large permanent vacuole: keeps cell rigid
    + Multiple rigid cells are arranged to form photosynthetic tissue
32
Q

Define diffusion

A

The spreading out of particles resulting in a net movement from an area of high concentration to an area of low concentration

33
Q

What is the concentration gradient?

A

The difference between two areas of concentration

34
Q

Explain 3 factors which increase the rate of diffusion?

A
  • Big concentration difference: Steep concentration gradient = fast diffusion rate
  • Increase temperature: Movement of particles speed up
  • Increase surface area of cell membrane: Increase area of which diffusion can take place = more of a substance can move in at a given time
35
Q

Name 2 dissolved substances which move by diffusion

A

Glucose, urea

36
Q

Name 2 gases which move by diffusion

A

Carbon dioxide, oxygen

37
Q

Define osmosis

A

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

38
Q

Describe isotonic solution

A

When the concentration of solutes in solution outside the cell is EQUAL to the internal concentration

39
Q

Describe hypertonic solution

A

When the concentration of solutes in solution outside the cell is GREATER THAN the internal concentration

40
Q

Describe hypotonic solution

A

When the concentration of solutes in solution outside the cell is LESS THAN the internal concentration

41
Q

Explain 2 ways osmosis can help cells

A
  • If a cell uses up water: the cytoplasm becomes more concentrated, meaning the fluid will become hypotonic so water will move into the cell
  • If more water is made: the cytoplasm becomes dilute, meaning the fluid becomes hypertonic so water moves out of the cell
42
Q

Explain 2 ways omosis can damage cells

A
  • If the solution outside the cell is too hypotonic: water will move into the cell but the cell will swell and may burst
  • If the solution outside the cell is too hypertonic: the cytoplasm will become too concentrated so water will move out of the cell but the cell may shrivel up and won’t survive
43
Q

Why do plants rely on osmosis?

A

To support their stems and leaves

44
Q

What is turgor pressure?

A

When water moves into the plant and the vacuole swells, pressing the cytoplasm against the plant cell wall.
Pressure builds up until no more water can enter the cell.

45
Q

Why is turgor pressure important?

A

It makes the cells hard and rigid, keeping the leaves rigid and firm

46
Q

Why should the fluid surrounding the cells always be hypotonic?

A

Will keep water moving in by osmosis in the right direction, resulting in turgid cells.

47
Q

What happens if the fluid is hypertonic to the cell? +What could also potentially happen?

A

Water will leave the cell by osmosis and the cells will not be firm and will become flaccid (soft).
If more water is lost, the vacuole and cytoplasm may shrink and the cell membrane will pull away from the cell wall (plasmolysis).

48
Q

Define plasmolysis

A

The shrinking of protoplasm as a result of water loss by osmosis

49
Q

Define active transport

A

The movement of substances from a more dilute solution to a more concentrated solution against a concentration gradient.

50
Q

List 3 things about how active transport works

A
  • Works against a concentration gradient
  • Requires energy from respiration
  • Across a partially permeable membrane
51
Q

Describe how cells carry out active transport through respiration

A

Cells respire, releasing the energy for active transport

52
Q

Describe the link between active transport and respiration

A

As rate of respiration increases, the rate of active transport increases

53
Q

Explain why active transport is useful for plants

A
  • Allows mineral ions to be absorbed into plant root hair from dilute solutions in the soil. Plants require ions for healthy growth.
54
Q

Explain why active transport is useful for humans

A
  • Allows sugar molecules to be absorbed from a low concentration (gut) to a high concentration (blood). Sugar molecules are used for cellular respiration.
55
Q

What happens to the surface area: volume ratio when organisms increase in size?

A

The surface area: volume ratio decreases

56
Q

What happens once the surface area: volume ratio decreases? + What does this result in ( 2 things)?

A

There will be an increased difficulty of exchanging materials.

  • Gases and food molecules can’t reach every cell inside an organism by simple diffusion.
  • Metabolic waste can’t be removed fast enough to avoid poisoning cells.
57
Q

Explain 4 factors which increase the effectiveness of an exchange surface

A
  • Large surface area for exchange
  • Thin membrane: Provides a short diffusion path
  • Efficient blood supply: Moves substances away from the surface, maintaining a steep concentration gradient
  • Being ventilated: Efficient gas exchange: maintains steep concentration gradient
58
Q

Explain how the alveoli is adapted for efficient exchange

A

Enormous surface area, rich blood supply

59
Q

Explain how the villi (small intestine) is adapted for efficient exchange

A

Large surface area, rich blood supply, short diffusion path

60
Q

Explain how plants are adapated for efficient exchange

A

Large surface area = efficient water and mineral ion uptake

+ Flat thin leaves, air spaces, stomata

61
Q

How are fish gills adapted for efficient exchange?

A

Made of stacks of thin filaments, each with a rich blood supply

AQA Biology (3 decks)

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