Transport in Cells

Question 1

What is diffusion?

Answer 1

Diffusion is the spreading out of particles resulting in net movement from an area of high concentration to an area of lower concentration, until the particles reach equilibrium (evenly distributed)

Question 2

Why does diffusion happen in both solutions and gases?

Answer 2

Because the particles are free to move about randomly

Question 3

Why is net movement more accurate?

Answer 3

The overall movement of particles is from high to low concentration, however as particles move randomly, some will occasionally move from low to high

Question 4

What is the concentration gradient?

Answer 4

The difference in concentration

Question 5

The bigger/steeper the concentration gradient…

Answer 5

the faster the diffusion rate

Question 6

What does a higher temperature do to the diffusion rate and why?

Answer 6

It will give a increased diffusion rate because the particles have more energy and therefore can move around faster

Question 7

As the dimensions of an object get smaller, the surface are to volume ratio gets…

Answer 7

bigger

Question 8

As objects increase in volume, they get a _____ surface area to volume relationship

Answer 8

smaller

Question 9

The higher the surface area to volume ration is, the _____ the rate of diffusion is, why?

Answer 9

higher, becuase larger surface area means more particles can pass through at once

Question 10

How are the lungs adapted to do diffusion? (3)

Answer 10

1. Lungs contain millions of tiny air sacs called alveoli, meaning a high SA:V - which means quick diffusion rates
2. Alveoli have walls that are 1 cell thick = a short diffusion path therefore easy diffusion
3. Alveoli have a constant supply of blood, meaning the concentration gradient is maintained and oxygen is always moving into the blood, or carbon dioxide out.

Question 11

How is the small intestine adapted to do diffusion? (3)

Answer 11

1. The small intestine contains millions of tiny folds called villi (which are covered in microvilli as well) meaning a high SA:V - which means quick diffusion rates
2. Villi have thin walls for a short diffusion pathway, meaning faster nutrient absorption
3. Villi have a constant blood supply, which maintains the concentration gradient, meaning nutrients are always moving into the blood

Question 12

How are leaves adapted for diffusion? (3)

Answer 12

1. Every leaf has a flattened shape to increase surface area, and SA:V ratio - which means quick diffusion rates
2. Leaves are thin, meaning a short diffusion pathway so gases can diffuse in and out easily
3. Leaves have stomata which are small holes on the underside of the leaf that allow gases to diffuse in and out easily

Question 13

How are fish adapted for diffusion? (3)

Answer 13

1. Fish gills are made of millions of filaments which are covered in lamellae, this means a high SA:V - which means quick diffusion rates
2. The gills have a constant blood supply, meaning the concentration gradient is maintained and gases are always diffusing in and out of the blood
3. Fish blood flows in the opposite direction to water which is better for diffusion

Question 14

What is Osmosis?

Answer 14

Osmosis is the movement of water from a dilute solution (high water concentration) to a concentrate solution (lower water concentration) through a partially permeable membrane

Question 15

What is a partially permeable membrane?

Answer 15

A membrane with very small holes in it, such that only tiny molecules such as water can pass through the membrane, and not bigger particles such as sucrose.

Question 16

What is lysis?

Answer 16

When a cell is left in a dilute solution, it becomes the concentrate solution and therefore, because of osmosis, water moves into the cell and it can get so filled with water it bursts, which is lysis.

Question 17

What is crenation?

Answer 17

When a cell is left in a concentrate solution, it becomes the dilute solution, and therefore becuase of osmosis all it’s water gets drawn out, so it shrivels and becomes crenated.

Question 18

Why can animals cells experience lysis and crenation, but not plant cells?

Answer 18

Animal cells don’t have a cell wall, which means nothing is maintaining its shape, therefore its able to expand so much it bursts, or shrivel up. Plant cells do have a cell wall, this maintains the shape of the cell, meaning its unable to burst or become crenated.

Question 19

To make a solution more concentrate you can?

Answer 19

1. Add more solute

2. Remove some solvent

Question 20

To make a solution more dilute you can?

Answer 20

1. Add some solvent

2. Take out some of the solute

Question 21

Hypertonic? - comparative keywords (must be used in comparison to another solution)

Answer 21

The concentrate solution, contains lot’s of solute

Question 22

Hypotonic? - comparative keywords (must be used in comparison to another solution)

Answer 22

The dilute solution, contains no/less solute (has lots of water)

Question 23

Isotonic? - comparative keywords (must be used in comparison to another solution)

Answer 23

Same concentration

Question 24

What is a dilute solution?

Answer 24

A solution that contains a high solvent concentration and a low solute concentration

Question 25

What is a concentrated solution?

Answer 25

A solution that contains a low solvent concentration and a high solute concentration

Question 26

Plants rely on osmosis to support their…

Answer 26

stem and leaves

Question 27

Through osmosis the _______ swells which presses the _________ against the ___ ____ until no more water can enter the cell, this pressure is known as ______

Answer 27

vacuole, cytoplasm, cell wall, turgor

Question 28

What is active transport?

Answer 28

Active transport is the net movement of particles against the concentration gradient, so from a lower concentration to higher concentration.

Question 29

Diffusion and Osmosis are p______ processes, therefore they don’t require __________ ______ to happen the ______ ________ of _________ is enough

Answer 29

Diffusion and Osmosis are passive processes, therefore they don’t require additional energy to happen, the random movement of particles is enough

Question 30

Active transport is an a_____ process, it requires __________ ______

Answer 30

Active transport is an active process, it requires additional energy

Question 31

Cells that do lot’s of active transport need lots of what organelle and why?

Answer 31

They need lot’s of mitochondria to release lot’s of energy through aerobic respiration becuase active transport goes against the concentration gradient and therefore requires additional energy.

Question 32

Active transport in root hair cells?

Answer 32

Plants need minerals ions from the soil for healthy growth however, the concentration of the minerals is usually higher inside the cell that in the soil since the cell is smaller and the ions in the cells are less dispersed.
Therefore, the cells need to do active transport not diffusion to get the minerals from an area of low concentration to an area of high concentration.

Question 33

Active transport in the gut?

Answer 33

Active transport is used in the gut when there is a lower concentration of nutrients in the gut and a higher concentration in the blood, therefore the nutrients must be taken into the blood against the concentration gradient.

Question 34

Where is the additional energy needed for active transport released from?

Answer 34

In the mitochondria by aerobic respiration