transport in cells

Question 1

What is diffusion

Answer 1

The random movement of particles from an area of high concentration to an area of low concentration

Question 2

How do you calculate net movement

Answer 2

Particles moving in - particles moving out

Question 3

What is net movement

Answer 3

The general movement of particles

Question 4

What are the factors that determine the rate diffusion

Answer 4

Concentration gradient, temperature , surface area and diffusion distance

Question 5

How does the concentration gradient affect the rate of diffusion

Answer 5

The greater the concentration gradient the quicker diffusion takes place

Question 6

How does temperature affect the rate of diffusion

Answer 6

As the gas or solution heats up the particles gain more kinetic energy and move around faster, this increases the random movement of the particles enabling them to diffuse more rapidly

Question 7

How does surface area affect the rate of diffusion

Answer 7

Our membranes are partially permeable, so by increasing the surface area through which the particles can move through diffusion will be faster

Question 8

How does size compare to surface area to volume ratio

Answer 8

The larger the organism the smaller the surface area to volume ratio

Question 9

List 3 adaptions for exchange

Answer 9

Increasing the surface area, so more particles can move at once
Have a short diffusion distance the particles have to travel
Increase the steepness of the concentration gradient to speed up the net flow of particles

Question 10

How are lungs adapted for exchange

Answer 10

1)a large number of small alveoli creates a large surface area for rapid diffusion of gases
2) A rich capillary blood supply brings french blood to the alveoli maintaining a steep concentration gradient
Ventilation refreshes the air in the lungs to maintain a step concentration gradient
3)a thin alveolar wall gives the shortest diffusion distance for the gasses

Question 11

How are the small intestines adapted for exchange

Answer 11

1)They have thousands of villi which in turn have numerous microvilli on their surface for large surface area
2) they have rich capillary lood supply to remove absorbed nutrients and maintain a steep concentration gradient
3)the walls are only one cell thick to keep the diffusion distance short

Question 12

How are plant roots adapted for exchange

Answer 12

1)The tip of the roots are covered in root hair cells which increase their surface area for absorption
2) transpiration in the leaves continuously pulls water up the plant creating a steep concentration gradient
3) there is only a short distance from the edge of the root to the xylem in the middle

Question 13

How are plant leaves adapted for exchange

Answer 13

1)There are stomata at the bottom of the leaf to allow carbon dioxide to diffuse into the leaf and oxygen out
2) the thin leaf shape minimises the diffusion distance for gasses
3) the air spaces in the spongy layer exposes a large surface area for gaseous exchange

Question 14

What is osmosis

Answer 14

The net movement of water from a dilute solution to a strong solution across a partially permeable membrane

Question 15

Osmosis model answer plan

Answer 15

1.Identify the hyper/hypotonic solution
2.State which way the water moves
3…..by osmosis through a partially permeable membrane
4.Describe the result eg swells up / shrivells up

Question 16

What will happen to an animal cell when the solution is hypotonic to it

Answer 16

(If the surrounding solution is too dilute we say it is hypotonic)
Water will enter the cells and can cause them to burst

Question 17

What will happen to an animal cell if the solution is hypertonic to it

Answer 17

(if the slution is too concentrated we say it is hypertonic)
Water will leave the cells, causing them to shrivel up

Question 18

What will happen to an animal cell when the surrounding solution is isotonic to it

Answer 18

(if the surrounding solution is the same concentration to the cell it is isotonic)
Under these conditions there will be no movement of water so the cells will remain the same size

Question 19

What will happen to a plant cell if it is placed in a hypotonic solution

Answer 19

Water will enter the cell causing the vacuole to swell up and pushing the cytoplasm against the cell wall
The wall will push back preventing the cell from bursting
The cell becomes swollen and turgid

Question 20

What will happen if a plant cell is placed in a hypertonic solution

Answer 20

Water will leave the cell so that it loses its rigid form and is called plasmolysed

Question 21

Tears are hypotonic to blood, a student mixes tears and blood and looks at it through a microscope what would she see

Answer 21

Red blood cells swelling and possibly bursting

Question 22

Why does grass remain upright

Answer 22

Due to turgor pressure, the internal pressure exerted by the contents of plant cells due to the presence of water in the vacuole

Question 23

In a drip, an infused, one uses physiologic water (=0.9% NaCl) instead of pure water. Why is that?

Answer 23

Because this means it would have the same concentration of solute (be isotonic) to the blood, if pure water were used it would be hypotonic compared to the blood causing them to swell and potentially burst

Question 24

How does diffusion distance affect the rate of diffusion

Answer 24

The shorter the diffusion distance the faster the rate of diffusion will be.

Question 25

What do you call a swollen blood cell and plant cell?

Answer 25

animal cell - lysed
Plant cell - turgid

Question 26

What do you call a shrivelled plant and animal cell

Answer 26

Animal cell - crenated
Plant cell- plasmolysed

Question 27

What is active transport

Answer 27

The movement of a substance from an area of low concentration to an area of high concentration across a partially permeable membrane. It requires energy

Question 28

How do you calculate percentage change in mass

Answer 28

Subtract final mass from original mass
Divide by original mass
Multiply by 100

Question 29

Why is it important all potato pieces come from the same potato

Answer 29

To ensure initial water content and solute concentration are relatively consistent

Question 30

Why is it important all potato pieces come from the same potato

Answer 30

To ensure initial water content and solute concentration are relatively consistent

Question 31

Explain 2 ways which active transport differs from diffusion

Answer 31

Active transport requires energy while diffusion doesn’t
Active transport moves substances against their concentration gradient while diffusion moves substances down the concentration gradient

Question 32

Why are plants not able to rely on diffusion to absorb mineral ions from the soil

Answer 32

Because the concentration of mineral ions in the soil is often lower than the concentration inside plant cells

Question 33

Why are plants not able to rely on diffusion to absorb mineral ions

Answer 33

Because the concentration of mineral ions in the soil is often lower than the concentration inside plant cells

Question 34

Explain why plants need mineral ions

Answer 34

To regulate their internal processes

Question 35

Emphysema is a disease that weakens and breaks down the walls of the alveoli explain why someone with this disease may suffer from lower energy levels during physical exercise

Answer 35

Because it weakens and breaks down the walls of the alveoli reducing, therefore reducing their surface area for gas exchange leading to lower oxygen uptake and higher carbon dioxide retention causing lower energy levels during physical exersize

Question 36

What is the function of the stomata

Answer 36

To allow plants to take in carbon dioxide for photosynthesis and to release oxygen

Question 37

What is the function of the stomata

Answer 37

To allow plants to take in carbon dioxide for photosynthesis and to release oxygen

Question 38

Give one function of the ribs

Answer 38

To protect the organs in the chest cavity eg lungs

Question 39

Give one function of the ribs

Answer 39

To protect the organs in the chest cavity eg lungs