Structure and Functions in Living Organisms - Transport

Question 1

why do unicellular organisms use diffusion for movement of substances?

Answer 1

• unicellular organisms are composed of a single cell, so have a large surface area to volume ratio
• this means they have an efficient rate of diffusion

Question 2

what is a transport system?

Answer 2

a system that provides a constant supply of necessary substances through a medium to cells via an exchange surface

Question 3

why do organisms need a transport system?

Answer 3

• multicellular organisms have a small surface area to volume ratio
• this means they have an inefficient diffusion rate, so the cell cannot rely ofn diffusion
• this means the organism needs a transport system

Question 4

what is the phloem?

Answer 4

a tube system that transports sucrose and amino acids from the leaves to where they are being stored/used

Question 5

what is the xylem?

Answer 5

a tube system that transports water throught the plant via transpiration

Question 6

what are the components of the blood?

Answer 6

red blood cells, white blood cells, platelets and plasma

Question 7

what is plasma?

Answer 7

liquid that functions as transport medium for carbon dioxide, digested food, urea, hormones and heat energy

Question 8

how are red blood cells adapted for their functions?

Answer 8

• contain haemoglobin that combines with oxygen to transport oxygen to respiring cells
• no nucles so theres more space for haemoglobin
• small and flexibile to squeeze through narrow capillaries for efficient transport
• thin cell membrane to reduce diffusion distance
• biconcave to increase surface area to volume ratio

Question 9

how are phagocytes adapted to their functions?

Answer 9

• sensitive cell surface membrane to detect pathogens
• digestive enzymes in cytoplasm to digest the pathogen
• irregular shaped nucleus to allow them to squeeze through narrow gaps to remove pathogens quicker

Question 10

how are lymphoctes adapted to their functions?

Answer 10

large nucleus containing multiple copies of dna to produce antibodies in large amounts

Question 11

how does the immune system respond to a pathogen?

Answer 11

• when pathogen is detected the lymphocyte will split into two cells
• one cell produces antibodies that decativate the antigens of pathogens
• the other cell will be a memory cell so the same antibodies can be produced again from the same antigen
• the phagocyte locates the pathogen via chemicals produced
• once the pathogen is encountered they will engulf and release digestive enzymes to digest the pathogen
• pathogen is removed

Question 12

how does deoxygenated blood travel throught the heart?

Answer 12

• deoxygenated blood is carried from respiring cells by the vena cava to the right atrium
• right atrium contracts to increase pressure, pushing the blood into the right ventricle throught the semilunar valve
• semilunar valve closes to prevent backflow
• right ventricle contracts to increase pressure, causing blood to be carried out via the pulmonary artery throught the atrioventricular valve
• atrioventricular valve closes to prevent backflow

Question 13

how does oxygenated blood travel throught the heart?

Answer 13

• oxygenated blood is carried from the lungs by the pulmonary vein to the left atrium
• left atrium contracts to increase pressure, pushing blood into the left ventricle through the semilunar valve
• semilunar valve closes to prevent backflow
• left ventricle contracts to increase pressure, causing blood to be carried out via the aorta

Question 14

how does heart rate change during exercise?

Answer 14

• during exercise, more energy is needed via respiration
• heart rate will increase to allow more oxygen transport in blood to respiring cells

Question 15

how does adrenaline effect heart rate?

Answer 15

• adrenaline increases blood glucose levels
• breathing and heart rate increases
• so more glucose and oxygen is transported in the bloodstream

Question 16

what factors increase the risk of coronary heart disease?

Answer 16

• poor diet increases the presence of cholesterol in the diet, increasing risk
• stress stimulates the secretion of hormones that increases blood pressure, increasing buildup of fatty plaques, causing chd
• smoking causes vasoconstriction, increasing the risk of fatty plaques building up, causing chd

Question 17

what are arteries?

Answer 17

• transport oxygenated blood away from the heart
• thick muscular walls to withstand high pressure
• narrow lumen maintains high pressure to pump blood around the body

Question 18

what are veins?

Answer 18

• transport deoxygenated blood towards the heart
• thin walls
• wide lumen to transport a large volume of blood
• valves to prevent backflow of blood under low pressure

Question 19

what are capillaries?

Answer 19

• facilitates gas exchange
• thin walls so diffusion distance is low
• narrow lumen to fit between cells and to increase surface area to volume ratio

Question 20

what does pulmonary, hepatic and renal mean?

Answer 20

pulmonary is associated with the lung
hepatic is associated with the liver
renal is associated with the kidney