Topic 1b Transport In Cells

Question 1

What is diffusion

Answer 1

Diffusion is the movement of particles from an area of high concentration to an area of low concentration

Question 2

Name the 4 particles that can diffuse through a cell membrane and explain why this is

Answer 2

Small molecules can diffuse through cell membranes

• oxeygen
• glucose
• amino acids
• water

Question 3

Give an example of molecules that cannot diffuse through cell embranes and explain why

Answer 3

Starch and protein

They are to large to permiate the cell membrane

Question 4

What three things can affect the rate of diffusion in a cell and why

Answer 4

(The concentration gradient)
- this is the difference in concentration of particles between the inside of the cell and outside of the cell. The bigger the visible difference between the amount of molecules inside and outside the cell the faster the rate of diffusion will be

(The temperature)
- higher the temp the faster the rate of diffusion due to the particles having more energy so they move around faster

(The surface area)
- the larger the surface area the more area particles have to pass through at one given time

Question 5

What is osmosis

Answer 5

Osmosis is the movement of water across a partially permiable membrane from a high water concentration to a region of lower water concentration

Question 6

If a cell is short of water where will the net movement occur

Answer 6

If the cell is short of water the solution inside the cell will be quit concentrated therefore the solution outside of the cell will be more dilute.
- the net movement of water in this case will be into the cell as the cell is short of water

Question 7

What is active transport

Answer 7

Active transport is the movement of particles against a concentration gradient from an area of lower concentration to an area of higher concentration using energy transfered during respiration

It can be used to move substances in and out of cells

Question 8

True or false active transport allows cells to absorb ions from very dilute substances

Answer 8

True

Question 9

Explain why root hair cells use active transport to take minerals up from the soil

Answer 9

Because there is usually a higher concentration of minerals in the root hair cells than the soil. Therefore active transport is used to take up the minerals against the concentration gradient

Question 10

Why do plants need to take up minerals and ions

Answer 10

Essential for plant health and growth

Question 11

Name one molecule that is taken up by active transport in the gut

Answer 11

Glucose

Question 12

Explain how active transport works in the gut

Answer 12

Active transport allows glucose and amino acids to be taken from the gut into the blood even though there is a higher concentration of glucose in the blood than the gut (the movement of nutrients is against the concentration gradient).
Glucose can then be to cells where it is used for respiration.

Question 13

What is the concentration gradient

Answer 13

The difference in concentration of particles between the inside of a cell and the outside of a cell.
The bigger the difference in particles the faster the rate of diffusion will be

Question 14

What is a solute

Answer 14

A solute is a dissolved substance

Question 15

Name the three ways in which substances move in and out of a cell

Answer 15

Diffusion - oxeygen and carbon dioxide are transfered between cells and the environment using diffusion during gas exchange

Active transport

Osmosis

Question 16

Give 2 ways in which dissolved substances can move into and out of a cell

Answer 16

Diffusion and active transport

Question 17

Give three ways in which exchange surfaces in animals may be adapted for effective exchange

Answer 17

• They have a short diffusion pathway/thin membrane so substances only have to travel a short distance in order to diffuse
• They have a large surface area so lots of substances can diffuse at once
• Exchange surfaces in animals have lots of blood vessels to get substances into and out of the blood quickly
• Gas exchange surfaces in animals are often ventilated too so air moves in and out

Question 18

Suggest and explain two features that an earthworm’s skin may have to make it effective as a gas exchange surface

Answer 18

Any of the adaptations

• So the worm may have lots of blood vessels in its skin to get gases in and out quickly
• It may have a large surface area so a lot of substance can be diffused at once
• It may have thin membrane so substances have a shorter distance to travel in order to diffuse

Question 19

Explain why some animals like elephants need a specialised organ system for gas exchange while earthworm’s don’t

Answer 19

Multicellular organisms (elephant) have a smaller surface area compared to their overall volume so not enough substances can be diffused from their outside surface to supply their entire volume.
Single cell organism (earthworm) have a large surface area in comparison to the volume so substances can exchange directly in and out across the cell membrane without a specialised gas exchange

Question 20

What are the Alveoli

Answer 20

The Alveoli are air sacs contained within the lungs that increase the surface area of the lungs where gas exchange takes place

Question 21

How are the Alveoli adapted to maximise gas exchange within the lungs

Answer 21

• An enourmous surface area 75m2 in humans so they are able to diffuse a lot of oxeygen at one time
• They have thin walls so the diffusion distance is short
• The lining of the alveoli are moist so the gases are able to dissolve easier
• They have a good blood supply as the capillaries are close by so there is a steep concentration gradient

Question 22

What are villi and how do they aid absorbtion of nutrients in the small intestine?

Answer 22

Villi are tiny little projections which cover the inside of the small intestine and aid the absorption nutrients e.g. glucose, amino acids
- This is done through the increasing of the surface area of the small intestine so that nutrients can be absorbed quicker

Question 23

What adaptations do villi have to increase absorption of nutrients in the small intestine?

Answer 23

large surface area

good blood supply to assist absorption quickly

Question 24

What are Stomata and what is their role in gas exchange in leaves?

Answer 24

Stomato are little holes on the leafs of plants. They allow gas exchange to take place with carbon dioxide into the leaf.
Oxygen (produced in photosynthesis) and water vapour out of the leaves through the stomata

Question 25

Describe how leaf adaptions have made it more efficient for gas exchange?

Answer 25

• Flattened shape of the leaves increases the surfaces area for diffusion in and out of the leaves
• The cell walls inside the leaves have air space in between them which increase the surface area giving more chance for carbon dioxide to get into the cells

Question 26

What are the chemical symbals for Oxygen, Water and Carbon dioxide?

Answer 26

Oxygen - O2
Water - H2O
Carbon dioxide - C02
All two are small

Question 27

What are Guard cells and what are there function?

Answer 27

Guard cells are cells which surround the stomato (2 either side)
If the plant is losing water through its leaves faster than the water absorbed through the roots the guard cells close to stop the plant losing more water.

Question 28

Where does gas exchange take place in fish?

Answer 28

Gas exchange takes place in the gills of fishes

Question 29

How do lamelle increase the efficiency of gas exchange across the gills of fish

Answer 29

They increase the surface area of the gills available for diffusion of gases therefore the rate of diffusion is increased

Question 30

How does the direction of blood flow in the lamella increase the efficiency of gas exchange in the gills

Answer 30

The direction of the blood flow helps maintain a large concentration gradient of oxygen between the water and the blood because it flows in the opposite direction. The concentration of oxeygen is always higher in the water than in the blood so the net movement of oxygen will be into the blood so as much oxygen as possible diffuses into the blood.

Question 31

If water in a lake becomes polluted the amount of oxygen dissolved in the water will be reduced. What effect would this have on the rate of diffusion of oxygen into the gas exchange of the organs in the fish living in the lake

Answer 31

The rate of diffusion will decrease because it would reduce the difference in the concentration of oxygen between the water and blood in the gills therefore reducing the concentration gradient

Question 32

In humans glucose is absorbed into the bloodstream in the small intestine. This is often done using active transport. Explain why glucose may be absorbed using active transport and why this requires respiration?

Answer 32

Because the concentration of glucose is higher in the the bloodstream than in the small intestine and the process of active transport requires energy which is provided by respiration

Question 33

How would damage to the villi in the small intestine affect the absorbtion of glucose and other nutrients. Explain your answer

Answer 33

The amount of nutrients absorbed would decrease. By damiging the villi the surface area will decrease affecting the amount of nutrients absorbed

Question 34

In what process is water absorbed into the bloodstream in the large intestine explain how this process works

Answer 34

Water is absorbed into the bloodstream in the intestine through osmosis. This is because there is a higher concentration of water in the large intestine than the bloodstream and the water moves from an area of higher concentration to a lower concentration.

Question 35

Who founded mitosis

Answer 35

Walter flemming

Question 36

Summarise the transport methods

Answer 36

Diffusion - movement of particles from higher to lower concentration

Osmosis - movement of water from region of higher water concentration to a region of lower concentration

Active transport - movement of particles against concentration gradient from a lower concentration to a higher concentration

Question 37

Describe the function of receptors in the skin

Answer 37

Detect and respond to stimulus converting this stimulus into an impulse which is sent to the brain

Question 38

What are the three main types of nerve cells (neurons)

Answer 38

sensory, motor and relay

Question 39

What is an effector and what are the 2 different types of effector and there responses

Answer 39

An effector is a muscle or a Gland that produces a specific response to a stimulus
Muscle - Contract to produce movement
Gland - Secrete enzymes and hormones

Question 40

Describe the reflex arc in detail

Answer 40

Stimulus is detected by a receptor
Electrical impulse pass from the receptor along a sensory neurone to the Central Nervous System (CNS)
A Chemical is released and diffuses across the synapse to a relay neurone
Relay neurone sends the electrical impulse to the motor neurone
The electric impulse passes down the motor neurone to an effector and a response is produced