Movement of Molecules Into and Out of Cells

Question 1

What is osmosis?

Answer 1

The movement of water molecules across a partially permeable membrane from an area of high water concentration to an area of low water concentration.

Question 2

What is a partially permeable membrane?

Answer 2

A membrane with very small holes in it that only tiny molecules like water can pass through.

Question 3

Describe the movement of water molecules during osmosis.

Answer 3

The water molecules move randomly both ways through the partially permeable membrane but there’s a steady net flow of water into the area of low concentration.

Question 4

What is tissue fluid?

Answer 4

Fluid that surrounds the cells of the body containing water, oxygen, glucose and other nutrients.

Question 5

How can one increase the amount of water moving into a cell?

Answer 5

The concentration of water around the cell will increase so that the water moves into the cell by osmosis.

Question 6

What happens if a cell has too much water?

Answer 6

The concentration will be higher in the cell than in the tissue fluid so the water will move out of the cell via osmosis.

Question 7

What is the purpose of sports drinks?

Answer 7

To replace water and ions lost through perspiration and replace the sugar used by the muscles during exercise.

Question 8

What four things should be considered when evaluating claims made by sports drinks companies?

Answer 8

• Is the report a scientific study, published in a reputable journal
• Was it written by a qualified, independent company?
• Was the sample size sufficient?
• Have other studies found similar results?

Question 9

What is active transport?

Answer 9

Active transport is the movement of particulars from an area of low concentration to an area of high concentration using energy and a carrier protein.

Question 10

What is a use of active transport?

Answer 10

Taking in remaining nutrients from the digestive system when the concentration will be higher in the blood.

Question 11

What is an exchange surface?

Answer 11

A surface through which gases and dissolved substances move during life processes.

Question 12

What are four ways that exchange surfaces are adapted?

Answer 12

• Thin so short diffusion pathway.
• Large surface area so lots of a substance can diffuse at once.
• Good blood supply to get nutrients in and out the blood quickly.
• Animals often have ventilated has exchange surfaces.

Question 13

What is the job of the lungs?

Answer 13

To transfer oxygen into and remove carbon dioxide from the blood.

Question 14

What are alveoli?

Answer 14

Little air sacs in the lungs covered in capillaries where gas exchange takes place.

Question 15

What happens in the alveoli?

Answer 15

• There is a higher concentration of oxygen in the alveoli so oxygen diffuses into the blood stream
• There is a lower concentration of carbon dioxide in the alveoli so carbon dioxide diffuses into them from the blood stream
• Air moves in and out of the alveoli via the bronchiole

Question 16

What are four adaptions of the alveoli?

Answer 16

• Enormous surface area
• A moist lining for dissolving gases
• Very thin walls
• Good blood supply from the capillaries

Question 17

What does the small intestine have to help with abortion of nutrients?

Answer 17

Villi

Question 18

How are villi adapted?

Answer 18

• Tgey have cell-thick surfaces for short diffusion pathways
• A very good blood supply from capillaries for quick absorption

Question 19

What is the breathing system?

Answer 19

How air gets in and out of your lungs.

Question 20

What is the thorax?

Answer 20

The top part of your body.

Question 21

What separates the thorax from the abdomen?

Answer 21

The diaphragm

Question 22

What protects the lungs?

Answer 22

The rib cage

Question 23

How does air enter the body?

Answer 23

Through the trachea. The air then goes down one of two bronchi (singular bronchus) which are both linked to a lung.

Question 24

What do the bronchi split into?

Answer 24

Bronchioles which feed into the alveoli.

Question 25

What is ventilation?

Answer 25

The movement of air in and out of the lungs.

Question 26

What happens when we breathe in?

Answer 26

• Intercostal muscles contract
• Rib cage moves up and out
• Diaphragm contracts to flatten
• Pressure on thorax decreased so it expands
• Air drawn in to the lungs

Question 27

What happens when we breathe out?

Answer 27

• Intercostal muscles relax
• Ribcage moves down and in
• Diaphragm relaxes and becomes dome shaped
• Volume of thorax decreases as pressure increases
• Air forces out lungs

Question 28

What is an iron lung?

Answer 28

An artificial ventilator in the form of a giant case.

Question 29

How does an iron lung work?

Answer 29

Air is pumped out of the case to cause pressure to drop allowing the lungs to draw in air. Air is then pumped into the case to force air out of the lungs.

Question 30

What is a problem with the iron lung?

Answer 30

It messes with the blood flow to the lower body.

Question 31

How do modern ventilators work?

Answer 31

Air is pumped into the lungs and then stops to allow the air to be released.

Question 32

What is an advantage or a disadvantage of having a modern ventilator?

Answer 32

+Doesn’t interfere with blood flow

-Can occasionally cause damage to lungs if they can’t cope with the artificial air flow

Question 33

Describe the movement of carbon dioxide into a leaf.

Answer 33

Carbon dioxide diffuses into the air spaces within the leaf through the stomata and then into the palisade leaf cells.

Question 34

Describe the movement of oxygen and water vapour out of a leaf.

Answer 34

Water vapour and oxygen first diffuse into the air spaces in the leaf from the palisade leaf cells and then diffuse out into the air through the stomata.

Question 35

Where is the exchange surface of a leaf found?

Answer 35

On the bottom.

Question 36

How are leaves adapted for photosynthesis?

Answer 36

• Stomata allow gas in and out

* Flattened shape increases surface area of exchange surface

Question 37

What happens if a leaf is losing more water than it gain through the roots?

Answer 37

The stomata are closed by the guard cells.

Question 38

What would happen to plants if they didn’t have guard cells?

Answer 38

The plants would lose so much water that they’d wilt.

Question 39

How many guard cells does each stomata have?

Answer 39

Two

Question 40

What happens to the guard cells at night?

Answer 40

They detect low light levels and so close the stomata to save water.

Question 41

Why does heat aid evaporation and water loss?

Answer 41

The heat gives the water more energy to evaporate.

Question 42

Why do dry conditions aid evaporation and water loss?

Answer 42

Water molecules will diffuse out of the leaf into the air.

Question 43

Why does wind help the evaporation and water loss?

Answer 43

Wind carries water vapour away from the leaf, maintaining a low concentration of water in the air around the leaf.

Question 44

Why do cells on the surface o plant roots have long hairs?

Answer 44

It gives the plant a larger surface area for absorbing water and mineral ions from the soil.

Question 45

How do mineral ions enter the root hair cells?

Answer 45

Active transport