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GCSE Triple Biology > Cell Biology > Flashcards

Cell Biology Flashcards

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1
Q

Define Diffusion

A

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

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2
Q

True or False: Diffusion only happens in gases?

A

False, it occurs in solutions and gases

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3
Q

What is the concentration gradient?

A

The difference in concentration

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4
Q

True or False: The bigger the concentration gradient, the faster the rate of diffusion.

A

True

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5
Q

How does the temperature affect the rate of diffusion?

A

A higher temperature will give a faster diffusion rate because the particles have more energy and will move around faster.

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6
Q

Cell membranes are semi-permeable. What does this mean?

A

It means they let some molecules through but not all molecules.

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7
Q

True or False: Dissolved substances can move in and out of cells by diffusion.

A

True

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8
Q

True or False: Particles can only move one way through a semi-permeable membrane

A

False, the movement is random so the particles can move both ways

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9
Q

What does a ‘net movement’ mean?

A

the overall movement of the particles

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10
Q

How does the surface area of the membrane affect the diffusion rate?

A

A larger surface means a higher diffusion rate because more particles can pass through at once.

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11
Q

Give three factors that can affect the rate of diffusion:

A

• Concentration gradient - the bigger the gradient, the faster the rate of diffusion
• Temperature - the higher the temperature, the faster the rate of diffusion
• Surface area of a cell membrane - the larger the surface area, the faster the rate of diffusion

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12
Q

Define Osmosis

A

Osmosis is the movement of water molecules across a partially permeable membrane from an area of high concentration to an area of lower concentration.

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13
Q

What is a hypotonic solution?

A

A solution with low solute concentration and a higher water concentration

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14
Q

What is a hypertonic solution?

A

A solution with a higher solute concentration and a lower water concentration

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15
Q

What is an isotonic solution?

A

A solution with the same solute concentration and the same water concentration in relation to another substance.

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16
Q

What are the two main stages of the cell cycle?

A
  1. Growth and DNA Replication
  2. Mitosis
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17
Q

What is the Cell Cycle?

A

The process by which cells divide to produce new cells

18
Q

What happens during Growth and DNA Replication?

A

The cell increases its number of subcellular structures and the DNA Replicates to form two copies of each chromosome

19
Q

What happens during mitosis?

A
  1. Chromosomes line up at the centre of the cell and are pulled apart by cell fibres. Two arms of each chromosomes go to opposite ends of the cell
  2. Nucleus divides and forms membranes around each new set of chromosomes which become the nuclei of each cell
  3. Cytoplasm and cell membrane divide and 2 new identical daughter cells are formed
20
Q

What is active transport?

A

The movement of substances from dilute to a concentrated solution, against the concentration gradient

21
Q

How is Active Transport important for plants?

A

It allows mineral ions to be absorbed into plant root hairs from dilute solutions in the soil.

22
Q

How is Active Transport important in the body?

A

It allows sugar molecules to be absorbed from lower concentrations in the gut into the blood so it can be carried to
the cells for respiration

23
Q

Where are Chromosomes found and what do they contain?

A

In the nucleus, they contain genes

24
Q

Fill in the gaps

A
25
Q

Fill in the gaps

A
26
Q

Magnification =

A

image size / real size

27
Q

What is a stem cell?

A

An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type

28
Q

Give one advantage and disadvantage of embryonic stem cells:

A

+ : Can differentiate into all other cells
- : Ethical objections, embryos can’t give consent

29
Q

What are the limitations of bone marrow stem cells?

A

They can only differentiate into blood cells

30
Q

Where are plant stem cells found and what can they be used for?

A

In the meristem at the tips of roots and shoots. They can be used to protect rare species from extinction because they can differentiate further after the first time

31
Q

What is therapeutic cloning and give one advantage of it?

A

Making stem cells from the person that needs treatment. It eliminates the ethical dilemma of consent and fear of rejection

32
Q

How does therapeutic cloning work?

A
  1. Take a donor egg and remove the DNA
  2. Insert the patient DNA into the donor egg
  3. Shock the egg to cause it to start to divide.
33
Q

How do prokaryotes replicate?

A

By Binary Fission

34
Q

What happens during binary fission?

A
  1. Circular DNA and plasmids replicate
  2. Cell gets bigger and the circular DNA strands move to opposite ends
  3. Cytoplasm begins to divide and new cell walls start to form
  4. Cytoplasm divides and 2 daughter cells are produced each with one copy of circular DNA and a variable number of plasmids
35
Q

Why are microorganisms not kept above 25°C in schools?

A

Because harmful bacteria will
form above 25°

36
Q

How are alveoli specialised to maximise diffusion?

A

• Large Surface Area
• Moist lining for dissolving gases
• Very thin walls
• A good blood supply

37
Q

How are villi specialised to maximise diffusion?

A

• Only 1 layer of surface cells
• Good blood supply to assist quick absorption
• Large Surface Area

38
Q

How do leaves maximise diffusion?

A

• Flattened shape increases exchange surface area
• Lots of stomata which enables gas exchange

39
Q

Why should a petri dish that is being used to grow bacteria be stored upside down?

A

To stop condensation falling onto the agar surface

40
Q

Why do multicelled organisms need specialist exchange surfaces but single celled ones don’t?

A

They have a smaller SA:V ratio so their outside surface isn’t enough to supply their entire volume

41
Q

What is meant by specialised?

A

A cell that has differentiated into a certain type of cell that has a specific function

GCSE Triple Biology (3 decks)

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