B3.1 (Movements of molecules)

Question 1

How is diffusion used in gas exchange in the lungs?

Answer 1

Oxygen diffuses from the alveolus in the lungs, an area of HIGH concentration, into the blood stream, an area of LOW concentration

Question 2

What is active transport?

Answer 2

The act of moving molecules form an area of LOW concentration to an area of HIGH concentration
It requires more energy (from respiration) to take place

Question 3

What cells use active transport for their purpose?

Answer 3

ROOT HAIR CELLS
- absorb ions from the soil
VILLI IN THE SMALL INTESTINE
- along with diffusion maximises the absorbtion of glucose etc

Question 4

How is active transport different from diffusion?

Answer 4

Active transport goes AGAINST the concentration gradient, requires energy and also requires PROTEIN CARRIERS IN THE CELL MEMBRANE

Question 5

What is osmosis?

Answer 5

The movement of WATER in and out of cells

Question 6

What happens in the process of osmosis?

Answer 6

Osmosis is the movement of water from a DILUTE solution - meaning the water content is HIGH - to a concentrated solution - meaning the water content is LOW- through a partially permeable membrane

Question 7

What happens to a cell when the concentration of solution is HIGHER outside the cell (HYPERTONIC)?

Answer 7

The cell becomes shrivelled or FLACCID
This is because the water moves into the concentrated solution (with less water)
In a plant, the structure becomes FLACCID as the cells shrink away from the cell walls

Question 8

What happens to a cell when the concentration of solution outside the cell is LOWER (HYPOTONIC)?

Answer 8

The cell becomes TURGID
This is because more water enters the cell as it has a highly concentrated solution outside meaning less water and more water inside

Question 9

What solution is a HYPOTONIC solution?

Answer 9

A LOW concentrated solution (more water)

Question 10

What solution is a HYPERTONIC solution?

Answer 10

A HIGH concentrated solution (less water)

Question 11

Why is it important for the concentrations of solution in and outside of an animal cell to be kept constant?

Answer 11

Animal cells do not have a cell wall so if they become TOO TURGID due to a HYPOTONIC solution, they could burst!!!

Question 12

What important factor aids the efficiency of diffusion?

Answer 12

• A short diffusion pathway

- A larger surface area than volume

Question 13

What are common adaptations to maximise substance exchange (diffusion etc)?

Answer 13

• A large surface area (FOLDED SURFACE)
• Thin exchange surface
• Good blood supply (Extensive capillaries, maintain concentration gradient)
• Ventilation to maintain gradient

Question 14

How are the villi adapted to digest food molecules?

Answer 14

• Folded to increase SA
• Single layer of thin cells
• Extensive capillary network to distribute absorbed food molecules

Question 15

Why can sports drinks be more useful than water at replenishing an athlete?

Answer 15

During exercise, an athlete loses minerals and ions as well as water however water can only replace water and sports drinks can replace the glucose and ions as well

Question 16

What are the functions of the lungs?

Answer 16

• Ventilation

- Gas exchange (swapping gases into the blood from the alveoli)

Question 17

When you inhale air, what route does it take to the lungs?

Answer 17

Mouth, Trachea, Bronchi , Bronchioles, Alveoli

Question 18

How do the intercostal muscles move when you INHALE?

Answer 18

They CONTRACT

This EXPANDS the muscles UPWARDS and OUTWARDS

Question 19

Does the diaphragm relax or contract on inhalation?

Answer 19

The diaphragm CONTRACTS

It moves DOWNWARDS to increase the volume of the chest

Question 20

How does the movements of the intercostals and diaphragm help inhalation?

Answer 20

Pressure inside the chest is LOWERED causing air to be sucked into the lungs

Question 21

What happens when you EXHALE?

Answer 21

• The intercostals RELAX, causing the ribs to go IN and DOWN
• The diaphragm RELAXES to decrease the volume of the chest
• Pressure inside the chest consequently INCREASES which forces air OUT

Question 22

What is a negative pressure ventilator?

Answer 22

A negative pressure ventilator artificially inhales for a patient by creating a vacuum that expands the diaphragm etc and naturally exhales when they return to normal

Question 23

What is a positive pressure ventilator?

Answer 23

A positive pressure ventilator forces inhalation by forcing air into the trachea and using the elasticity of organs to create natural exhalation

Question 24

What are the advantages + disadvantages of NPVs?

Answer 24

+ effective at treating polio

• Patient is resticted in full body machine
• Vacuum can cause bleeding in lower abdomen and body

Question 25

What are the advantages and disadvantages of PPVs?

Answer 25

+ Useful in operations
+ Effective at ventilating lungs

• Long term ventilation requires surgery to insert the tube in the neck

Question 26

How do the alveoli exchange CO2 in the blood for O2?

Answer 26

• Blood arriving at the alveoli has a high concentration of CO2
• This DIFFUSES into the alveoli
• Meanwhile, the Oxygen diffuses into the blood following the concentration gradient

Question 27

What do the oxygen and haemoglobin in the blood combine to form?

Answer 27

Oxyhaemoglobin

Question 28

What are the adaptations of the alveoli?

Answer 28

• Large SA due to folds
• One cell thick walls
• Capillary blood supply
• Ventilation removing waste CO2 and replenishing O2

Question 29

What is the role of roots in a plant?

Answer 29

To absorb water and minerals via OSMOSIS and ACTIVE TRANSPORT

Question 30

How is water used in a plant?

Answer 30

• Photosynthesis
• Keeping the cells TURGID
• Cooling the leaves through evaporation

Question 31

How are root hair cells adapted to maximise their absorbtion efficiency?

Answer 31

• Finger like protrusions mean a large SA
• These protrusions also penetrate between soil particles shortening the diffusion pathway
• Lots of mitochondria to release energy needed for ACTIVE TRANSPORT

Question 32

How are leaves adapted to absorb CO2 and light for photosynthesis?

Answer 32

• Flattened shape -> Increases surface area
• Thin -> Short diffusion pathway
• Stomata -> Can open to allow diffusion of CO2 in and O2 out
• Internal air spaces in spongy mesophyll layer -> Increase SA to absorb more CO2
• Guard cells -> Adjust size of stomata