Exchange and transport in animal

Question 1

Explain the need for transporting substances in and out of organisms.

Answer 1

• lungs excrete carbon dioxide
  – kidneys remove urea
• body moves substances into body
  
  • oxygen + glucose
    # dissolved food molecules and mineral ions

Question 2

Why is there a limit to size of cells?

Answer 2

As cells get bigger the sa:v ratio becomes smaller. If it becomes too small, the cell cannot beg raw materials fast enough

Question 3

Explain how alveoli are adapted for gas exchange

Answer 3

• moist lining -> dissolve gases
• big surface area -> oxygen diffuses out lungs quickly
• one cell thick - minimise distance gas has to diffuse over
• good supply -> maintain concentration gradient of CO2 and O2

Question 4

What’s gas exchange in alveoli?

Answer 4

1 ) blood enters with high carbon dioxide and low oxygen concentration
2) alveolus has high co2 concentration and low concentration of co2
3) body leaves w/low co2 concentration and high o2

Question 5

Describe factors affecting rate of diffusion.

Answer 5

1) distance - diffuse faster when there’s less distance
2) concentration gradient - bigger the difference, steeper the concentration gradient is to where they’re diffuse to. if there’s more molecules on one side, there make to move across & faster to diffuse
3) surface area: the more surface there is for molecules to travel across, faster they get to the other side

Question 6

Calculate the rate of diffusion using Fick’s law:

Answer 6

rate of diffusion α surface area × concentration difference / thickness of membrane

Question 7

What are the functions of blood vessels?

Answer 7

1) arteries - carry blood away from heart
2) capillaries : involved in exchange of materials
3) veins - carry blood to heart

Question 8

How are the structure of the arteries adapted to their function?

Answer 8

• thick layers -> withstand increase of blood pressure & wave of stretching passes along artery when heart squirts blood into arteries
• thick layers of muscle -> strong
• elastic fibres - stretch and relax under high pressure so blood flows smoothly

Question 9

How are the structure of the capillaries adapted to their function?

Answer 9

narrow -> able to squeeze past gaps in lungs and carry blood really close to cells to exchange materials
one cell thick -> increases rate of diffusion by decreasing distance

Question 10

How are the structure of the veins adapted to their function?d

Answer 10

• thin walls -> blood flows under low pressure
• valves - prevent back flow

Question 11

How are the structure of the red blood cells adapted to their function?

Answer 11

• biconcave disc shape -> large surface area to absorb oxygen
• lots of haemoglobin -> binds with oxygen to release again into tissues
  no nucleus -> more space for haemoglobin and to absorb oxygen

Question 12

How are the structure of the white blood cells adapted to their function?

Answer 12

1) phagocytes: engulf foreign cells / unwelcome organisms
2) lymphocytes- produce antibodies that stick to foreign cells and destroy them

Question 13

How are the structure of the platelets adapted to their function?

Answer 13

• small fragment of cells without nucleus
• help clot blood when wounded to stop blood pouring out and microorganisms entering
• lack of platelets cause clot issues -> excessive bleeding and bruising

Question 14

What is plasma?

Answer 14

pale straw coloured liquid that carries dissolved substances

Question 15

How does blood travel through the circulatory system?

Answer 15

1) deoxygenated blood right enter atrium via vena cave -> right ventricle -> lungs in pulmonary artery
2) Oxygenated blood:
heart -> pulmonary vein -> light atrium -> left ventricle -> rest of body via aorta

Question 16

Why do muscle walls in the heart vary?

Answer 16

The pressure applied differed - high blood pressure when blood is pumped

Question 17

What could cause cardiac arrest?

Answer 17

muscle walls in heart contracts hard enough so heart can pump blood to all the of the body, when blood stops flowing in arteries this can cause cardiac arrest.

Question 18

What’s the calculation for cardiac output?

Answer 18

cardiac output (l/min)= stroke volume (l/beat)× heart rate (beats/min)

Question 19

How do people who do exercise differ to those who don’t in stroke volume?

Answer 19

Regular exercise makes strength of heart muscles stronger so they are able to carry a bigger stroke volume thus the heart beats slowly to achieve the same cardiac output as those who don’t exercise.

Question 20

What’s cellular respiration?

Answer 20

an exothermic reaction which occurs continuously in living cells to release energy for metabolic processes, including aerobic and anaerobic respiration

Question 21

Compare the processes of aerobic respiration with anaerobic respiration.