Chapter 8 - Exchange and Transport In Animals

Question 1

Exchange of substances in organsims

Answer 1

• All organisms must take in substances that they need from the environment
• Cells need oxyge for aerobic respiration which produces carbon dioxide as a waste product. These two gases move between cells and the environment by diffusion
• Water is taken in by osmosis. In animals, dissolved food molecules and mineral ions diffuse along with it
• Urea diffuses from cells to the blood plasma for the removal from the body by the kidneys

Question 2

Surface area to volume ratio

Answer 2

• How easy it is for an organism to exchange substances is dependent on the surface to volume ratio
• Just by comparing the surface area to the volume
• A higher surface area to volume ratio is better so 6:1 is better than 2:1
• Some organisms have methods to expand their surface area

Question 3

Multicelluar organisms need exchange surfaces

Answer 3

• In single celled organisms, gases and dissolved substances can directly diffuse in and out of the cells due the large surface area to volume ratio
• Multicelluar organisms have a smaller surface area to their volume. This makes it difficult to exchange substances across their entire volume across their outside surface area alone. So they need some form of exchange surface for efficent diffusion

Question 4

Rate of Diffusion

Answer 4

• Dependent on three things
• Distance - substances diffuse more quickly when they have not got as far to move
• Concentration difference - diffuse faster if there are more particles to move
• Surface area - more area to move across

Question 5

Gas exchange - Occurs in alveoli

Answer 5

• The job of the lungs is to transfer oxygen to the blood and remove waste carbon dioxide
• To do this, lungs contain millions of air sacks where gas exchange takes place called alveoli
• Blood arriving at the alveoli has returned from the lungs from the rest of the body. This blood here is deoxygenated

Question 6

How the alveoli work

Answer 6

• Oxygen diffuses out of the alveoli and into the blood where there is no oxygen and carbon dioxide goes the other way
• The alveoli is specialised to maximise diffusion
• They have moist lining
• A good blood supply to maintain a constant concentration
• Very thin walls to minimise distance and a large surface area

Question 7

Fick’s law

Answer 7

Rate of diffusion = surface area x concentration difference
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Thickness of membrane

Question 8

Red blood cells

Answer 8

• The job of the RBC is carry oxygen from the lungs to all the cells in the body
• They have a bioconcave shape to give a large surface area to diffuse
• No nucleus to have more space to carry oxygen
• Contain a red pigment called haemoglobin which contains iron
• In the lungs, haemoglobin binds to oxygen to from oxyhemoglobin. In body tissues, they unbind to release oxygen into cells

Question 9

White Blood cells

Answer 9

• Phagocytes are WBC that can engulf unwelcome microbes
• Lymphocytes are white blood cells that oroduce antibodies against microbes. Some produce antitoxins to neutralise any toxins
• When there is an infection, WBCs multiply to fight it

Question 10

Platelets

Answer 10

• Help the blood clot
• Small fragments of cells
• Clot to cover a wound, this stops microbes going and blood coming out
• Lack of platelets can lead to excessive bleeding

Question 11

Plasma

Answer 11

• Carrier in the blood stream
• Carries soluble products of digestion such as amino acids and glucose
• Carbon Dioxdie, Urea, Hormones, Proteins and antibodies

Question 12

Functions of blood vessels

Answer 12

• Arteries - carry blood away fromt the heart
• Capillaries- involved in the exchange of materials
• Veins - carry blood to the heart

Question 13

Arteries

Answer 13

• Carry blood under high pressure
• The heart pumps blood out at high pressure whcih means the walls need to be strong
• The walls contain thick layers of muscle to make them strong

Question 14

Capillaries

Answer 14

• Arteries branch into the,
• Really small
• Narrow so they can squeeze in to gaps between cells. They can carry blood close to cells and exchange witht them
• Have permeable walls
• Supply oxygen and remove carbon dioxide
• Only one cell thick, which minimises distance

Question 15

Veins

Answer 15

• Capillaries eventually join up to veins
• Blood is at lower pressure, so they are not as thick
• Have bigger lumen to aid blood flow despite the low pressure
• Have valves to maintain blood flow in the correct direction

Question 16

Double circulatory system in mammals

Answer 16

• The heart pumps blood in two circuits. One pumps deoxygenated blood to the links to get oxygen and thr other pumps oxygenated blood to other organs of the body to deliver oxygen, deoxygenated then returns to the body
• Fish have a single system

Question 17

Heart

Answer 17

• Right atium of the heart recieves deoxygenated blood from the body
• The deoxygenated blood moves through to the right ventricle which pumps it into the lungs through the pulmonary artery
• Left atrium recieves oxygenated blood from the lings via the pulmonary vein
• Left ventricle pumps oxygenated blood the rest of the body via the aorta

Question 18

Role of valves

Answer 18

Prevent backflow (Triscupid, bicsupid and semi-lunar)

Question 19

Cardiac output

Answer 19

• How much blood is pumped by a ventricle every minute
• Cardiac output = Heart rate x Stroke volume
• Heart rate is numbe of beats per minute (bpm)
• Stroke volume is the volume of blood pumped by one ventricle each time it contracts

Question 20

Respiration

Answer 20

• Celluar respiration releases energy
• Respiration goes into every cell of all living organism
• It the process of transferring energy from the breakdown of organic compounds
• Because energy is transferred to the environment, respiration is exothermic
• There are two types of respiration : Aerobic and Anaerobic

Question 21

Aerobic respiration

Answer 21

• Occurs when oxygen is available
• Aerobic means with oxygen and is the most efficent way of transforming energy from glucose
• Usually occurs in plants and animals

Question 22

Anaerobic respiration

Answer 22

• When you do vigourous excersie, your body can not supply enough oxygen to muscles. You have to start anaerobically respiring
• It transferes less energy and is less efficent. Glucose is only partially broken down. Lactic acid is produced
• Lactic acid builds up and causes pain and cramps

Question 23

Anaerobic respiration in plants

Answer 23

• Produce ethanol instead of lactic acid