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B2 Flashcards

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1
Q

What is diffusion?

A

Diffusion is the net (overall) movement of particles from a region of high to a region of low concentration

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2
Q

Particles move … a concentration gradient in diffusion

A

Down

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3
Q

Where does diffusion occur in the body?

A

In all cells, as glucose and oxygen diffuse into them for respiration
Carbon dioxide diffuses out of respiring cells as it is toxic

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4
Q

What is osmosis?

A

Osmosis is the diffusion of water molecules across a selectively permeable membrane. It is from a high water potential to a low water potential.

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5
Q

What is water potential?

A

Water potential is the concentration of free water molecules. Water has the highest possible water potential (0). The more concentrated a solution, the lower its water potential.

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6
Q

Particles move … a concentration gradient in osmosis

A

down

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7
Q

What happens when the surroundings have a higher water potential than the cell in a plant cell?

A

The cell takes up water by osmosis, which increases its turgor pressure. The cell becomes turgid.

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8
Q

What happens when the surroundings have a higher water potential than the cell in a animal cell?

A

The cell takes up water by osmosis, swells and may burst. This is known as lysis.

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9
Q

What happens when the surroundings have a lower water potential than the cell in a plant cell?

A

The cell loses water by osmosis, and becomes flaccid (soft). Eventually the cell contents collapse away from the cell wall, which makes it a plasmolyse cell

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10
Q

What happens when the surroundings have a lower water potential than the cell in a animal cell?

A

The cell loses water by osmosis, which makes it crenated (it crinkles)

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11
Q

What happens when the surroundings have an equal water potential as the plant cell?

A

No net movement of water. The cell remains the same.

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12
Q

What happens when the surroundings have an equal water potential as the animal cell?

A

No net movement of water. The cell remains the same.

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13
Q

What is active transport?

A

Active transport allows cells to move substances from a low concentration to a high concentration.

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14
Q

Particles move … a concentration gradient in active transport

A

against

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15
Q

Examples of active transport - digestion, nerve cells and minerals from soil

A

Digestion - the small intestine breaks carbohydrates down into glucose, which is actively transported into the bloodstream through the villi
Nerve cells - Sodium ions are pumped out of the cell when potassium ions are pumped in
Minerals from soil - Active transport moves nitrate ions across the cell membrane and into the root cell from protein growth

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16
Q

What are 3 key features for active transport?

A

Particles are transported against a concentration gradient
ATP is required, which comes from respiration
The process makes use of carrier proteins in the cell membrane

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17
Q

What are carrier proteins and how do they work?

A

Carrier proteins are special proteins that span the width of the cell membrane. Energy is transferred from an energy store so it can change shape or rotate. The carrier protein transports the molecule into the cell.

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18
Q

What does the rate of respiration have on the rate on active transport?

A

As active transport requires ATP, the rate at which is occurs depends on the rate of respiration

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19
Q

What is mitosis?

A

Mitosis is the process by which body cells divide. Each cell divides to produce 2 genetically identical daughter cells

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20
Q

What is the cell cycle and what are its stages?

A

The cell cycle is the process of cell growth and division. It has 4 stages - DNA replication, movement of chromosomes, cytokinesis and growth of daughter cell

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21
Q

How is DNA replicated?

A
  1. The DNA molecule unzips to form 2 separate strands
  2. Free nucleotides in the nucleus line up against each of the strands following the rule of complementary base pairing
  3. DNA base pairs form, and once the whole strand is complete, there are 2 identical molecules of DNA
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22
Q

How do the chromosomes move?

A
  1. The chromosomes line up across the centre of the cell
  2. The two identical copies of each chromosome, formed when the DNA replicated, separate and move to opposite ends of the cell
  3. Each end now contains a full set of identical chromosomes
  4. Two new nuclei now form
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23
Q

What is cytokinesis?

A

When the cell membrane pieces inwards and outwards to split off the 2 nuclei into two new genetically identical daughter cells

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24
Q

Why is the cell cycle a cycle?

A

As the daughter cells formed will then begin replicating their own DNA and the cell cycle will continue

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25
Q

Explain the importance of cell differentiation

A

Cell differentiation is when a cell becomes specialised to perform a particular job. This is important as it makes the entire organism more efficient as life processes are carried out more effectively

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26
Q

Name some examples of specialised cells

A

Sperm cells, Fat cells, Red blood cells, Ciliated cells and palisade cells

27
Q

What are the functions of stem cells?

A

Stem cells are undifferentiated cells, that divide by mitosis which then differentiate and become specialised. This produces a range of different cell types for development, growth and repair.

28
Q

Where are stem cells present?

A

Animals - embryos and various body tissues (animals)

Plants - meristems (particular parts of the plant that grow)

29
Q

What are the differences between embryonic and animal stem cells (2)?

A

Embryonic stem cells have the ability to differentiate into all cell types, while animal cells can different into some, but not all cell types
Embryonic stem cells are found in embryos while animal cells are found in various body tissues like the brain, bone marrow, skin and liver

30
Q

Why do we need exchange surfaces?

A

As some substances need to enter and others need to leave the body

31
Q

Why do we need transport systems in multicellular organisms?

A

As multicellular organisms have a low surface area to volume ratio, so their diffusion distances are large

32
Q

How are substances transported in alveoli?

A

Oxygen moves into the bloodstream by the diffusion, and carbon dioxide passes out by diffusion

33
Q

How are substances transported in the small intestine?

A

Digested food molecules are absorbed into the blood from the small intestine

34
Q

What does the circulatory system carry which is toxic?

A

Urea is toxic, so it is transported to the kidney where it is removed

35
Q

What is the plants main transport system and what does it carry?

A

Xylem tubes carry water and mineral ions around a plant, and phloem tubes transport sugars and amino acids.

36
Q

Describe and draw a diagram of the human circulatory system

A

The circulatory system is made up of the heart and blood vessels
see p.g. 74

37
Q

How is the circulatory system related with the gaseous exchange system?

A

The blood transports oxygen for respiration, and carries away waste products such as carbon dioxide

38
Q

Why do humans need a double circulatory system?

A

As blood needs to be quickly transported around the body

39
Q

Draw a diagram of an artery and explain its features

A

Thick and muscular arterial wall allows blood to leave at a very high pressure

40
Q

Draw a diagram of a vein and explain its features

A

Thin vessel walls as pressure is low

One way valves keep the blood flowing back to the heart

41
Q

Draw a diagram of a capillary and explain its features

A

Link arteries and veins in tissues and organs.

Semipermeable walls are only one cell thick

42
Q

What is the heart made from, and why are they unusual?

A

The heart is made of cardiac muscle, a type of muscle only found in the heart.
They contract without receiving a nerve impulse from the brain

43
Q

Draw a diagram of the heart and locate its chambers and valves

A

see p.g. 76

44
Q

How are red blood cells adapted to their transport functions in the blood?

A

They have no nucleus and contain haemoglobin.

45
Q

How are plasma adapted to their transport functions in the blood?

A

Over 90% of plasma is water, and many materials are transported by being dissolved in plasma

46
Q

Describe the process of translocation

A

Translocation is when the phloem tissue transports dissolved sugars produced during photosynthesis, and other soluble food molecules, from the leaves to the other areas of the plant

47
Q

How are the xylem adapted to their function in a plant and draw a diagram to show this?

A

Xylem vessels are made from dead xylem cells
Tubes in which the water and dissolved mineral ions can flow
The rest of the xylem cellulose cell walls are thickened

48
Q

How are the phloem adapted to their function in a plant and draw a diagram to show this?

A

Phloem vessels are made of living cells

The cell walls of these cells don’t completely break down, and sieve plates are formed instead

49
Q

What are sieve plates?

A

Sieve plates are small holes in the end wall which allow dissolved sugars to pass through

50
Q

What do the connection of phloem cells form?

A

It effectively forms a tube which allows dissolved sugars to be transported

51
Q

Describe the process of transpiration

A

Transpiration is the loss of water from a plants leaves. The water lost must be replaced, by uptake through the routes

52
Q

How are water and mineral ions taken up the plants?

A

Water and mineral ions travel from cell to cell until they reach the xylem vessels

53
Q

What is the transpiration stream?

Draw a labelled diagram to show this

A

The constant flow of water from the roots, through the xylem and out of the leaves is called the transpiration stream. see. p.g.80

54
Q

What is the role of the stomata and guard cells?

A

The stomata allow carbon dioxide to diffuse in for photosynthesis. Guard cells allow the stomata to open and close

55
Q

What happens while the stomata are open?

A

Water diffuses out of the leaf (high concentration of water vapour) into the air (low concentration of water vapour)

56
Q

How do the stomata open?

Draw a diagram for this

A

When there is lots of light and water, guard cells take up water by osmosis, making them turgid, causing the stomata to open

57
Q

How do the stomata close?

Draw a diagram to show this

A

When there is low light and water, guard cells lose water by osmosis, which makes them floppy, causing the stomata to close.

58
Q

Draw an annotated diagram showing the overall process of transpiration

A

see p.g. 81

59
Q

How can a simple potometer be used to investigate factors affecting the rate of water uptake?
Draw a diagram explaining this

A
  1. Take an air bubble into the capillary tube
  2. As water moves into the shoot and evaporates from its leaves, the air bubble will move towards the plant
  3. Measure how fast the air bubble travels, which will give an idea of the rate of transpiration
  4. Repeat the experiment, changing the environmental conditions
60
Q

How do you measure the rate of transpiration?

A

rate of movement = distance air bubble travels (mm) / time air bubble takes to travel (s)

61
Q

What is the effect of light intensity on the rate of transpiration? Draw a graph to show this

A

As light intensity increases rate of transpiration increases as stomata open, so more water evaporates, until its maximum rate when all stomata are open

62
Q

What is the effect of air movement on the rate of transpiration? Draw a graph to show this

A

The faster the air moves the faster the water molecules move, so more water diffuses more quickly out of the leaf, increasing the rate of transpiration

63
Q

What is the effect of temperature on the rate of transpiration? Draw a graph to show this

A

As you increase the temperature, more water evaporates out of the cells more quickly, increasing the rate of transpiration

Biology (11 decks)

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