B1: Cell Structure And Organisation Flashcards

1
Q

How do you find out what the magnification of an object is?

A

Magnification = size of image/size of real object

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2
Q

What is the function of the cytoplasm?

A
  • Liquid gel where organisms are suspended
  • Where most chemical reactions for life take place.
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3
Q

What is the function of ribosomes?

A
  • Where protein synthesis takes place (the process of making all proteins for the cell)
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4
Q

What is the function of mitochondria?

A
  • Realease energy for the cell by aerobic respiration.
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5
Q

What is the function of the cell membrane?

A
  • To control the passage of substances in and out of the cell.
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6
Q

What is the function of chlorophyll?

A
  • To absorb light so that the plant can make food by photosynthesis.
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7
Q

How are eukaryotes and prokaryotes different?

A

Genetic Material:

  • In Eukaryotic cells the genetic material is enclosed in a nucleus.
  • In Prokaryotic cells the genetic material is not enclosed in the nucleus.

Mitochondria:

  • Eukaryotes have mitochondria
  • Prokaryotes do not have mitochondria.

Prokaryotic Cells are also always smaller than Eukaryotic Cells.

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8
Q

What are plasmids?

A
  • Small rings of DNA.
  • Code for specific features such as antiobiotic resistance.
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9
Q

Is bacteria prokaryotic or eukaryotic?

A

Prokaryotic.

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10
Q

Examples of specialised cells in animals?

A
  • Nerve cells
  • Muscle cells
  • Sperm cells
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11
Q

How are nerve cells specialised? (3)

A
  • Lots of dendrites that make connections to other cells.
  • Axons that carry the impulse from one place to another.
  • Synapses are adapted to pass the impulse to another cell or between a nerve cell and a muscle cell.
  • Myelin Sheath for insulation and it speeds up the electrical impulses
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12
Q

How are muscle cells specialised? (3)

A
  • Contain proteins that slide over each other and make the fibres contract
  • Contain many mitochondria to transfer energy needed for chemical reactions to take place
  • Store glycogen, which can be broken down and used in cellular respiration by the mitochondria to provide energy needed for the fibres to contract.
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13
Q

How are sperm cells specialised? (4)

A
  • Long tail helps it to move.
  • Middle section is full of mitochondria, which provide energy for the tail.
  • Large nucleus contains genetic information to be passed on.
  • Acrosome stores digestive enzymes to break down the outer layers of the egg
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14
Q

Give examples of specialised plant cells?

A

Root hair cells, photosynthetic calls’ xylem cells and phloem cells

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15
Q

How are root hair cells specialised? (3)

A
  • Increased surface area for water to move into the cell
  • Permanent vacuole that speeds up movement of water by osmosis from the soil across the root hair cell
  • Many mitochondria to transfer energy needed for active transport
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16
Q

How are photosynthetic cells specialised? (3)

A
  • Contain specialised chloroplasts
  • Usually positioned in continuous layers in the leaves and outer layers of the stem so they absorb as much light as possible
  • Large perm vacuole that keeps them rigid as a result of osmosis - keep the lead spread out to absorb as much light as possible.
17
Q

How are xylem cells specialised? (2)

A
  • Alive at first but die and form long hollow tubes to allow water and mineral ions to move easily through them
  • Spirals is lignin make them very strong and help them to withstand pressure of water.
  • Also help support phloem.
18
Q

How are phloem cells specialised? (2)

A
  • Cell walls between the cells break down to form special sieve plates.
  • Allow water carrying dissolved food to move freely
  • Supported by companion cells which transfer energy and support them.
19
Q

What is diffusion?

A
  • The spreading out of the particles of gas of any substance in a solution (a solute).
20
Q

What is the net movement of diffusion ?

A
  • From high to low concentration, down the concentration gradient.
21
Q

What affects the rate of diffusion?

A
  • Difference in concentrations
  • The temperature
  • The available surface area
22
Q

What substances diffuse in out body?

A
  • Glucose
  • Urea
  • Gases (such as oxygen and carbon dioxide) move out and into cells
23
Q

What is osmosis?

A
  • A dilute solution to a concentrated solution.
  • The movement of water particles from an area of high water concentration to an area of low water concentration across a partially permeable membrane.
  • Down the concentration gradient.
24
Q

Why is osmosis important in plants?

A

To maintain turgor (rigidity)

25
Q

What is isotonic?

A
  • When the concentration of the solution is the same inside and outside the cell
26
Q

What is hypertonic?

A
  • When the concentration of a solution is higher outside the cell.
27
Q

What is hypotonic?

A
  • When the concentration of a solution is higher inside the cell.
28
Q

What is plasmolysis?

A
  • When the vacuole and cytoplasm shrink and the cell membrane is pulled away from cell wall
29
Q

Where does active transport occur? (2)

A
  • Small intestine - uptake of sugar
  • In the roots (root hair cells)
30
Q

What is active transport?

A
  • The movement of substances from a dilute solution to a more concentrated solution.
  • Against the concentration gradient.
  • The movement of particles from an area of low concentration to an area of high concentration against a concentration gradient using energy from respiration.
31
Q

What is the surface area to volume ratio?

A

As an object gets bigger, the ratio of the surface area to volume falls.

32
Q

Why do most exchange surfaces usually have a large surface area and thin walls?

A

To give a shorter diffusion distance

33
Q

What is the importance of diffusion in animal and plant cells?

A
34
Q

Why do animal cells burst in a hypotonic solution?

A

They do not have a cell wall.

35
Q

Which organism has a higher surface area: volume ratio? A whale or a fly?

A

A fly. They have more surface area per unit of volume.

36
Q

State one adaptation cells may need if they need to carry out active transport.

A

Lots of mitochondria – to allow a lot of energy to be released for active transport.

37
Q

Explain how SA:V ratio of an organism affects the way it exchanges materials with the environment.

A
  • It affects how quickly an organism can exchange the materials with the outside world.
  • Smaller ratio means diffusion alone cannot provide sufficient gas and food molecules to cells and metabolic waste cannot be removed quickly enough.