exchange

Question 1

what characteristics do exchange surfaces show?

Answer 1

– large SA relative to V of organism to increase rate of exchange
– very thin short diff dist
– selectively permeable
– movement of the enivronmental medium
– a transport system to ensure the movement of the internal medium

Question 2

what is the equation for rate of diffusion?

Answer 2

(surface area x diff in conc) / length of diff path

Question 3

What three ways do gases move in and out of the tracheal system?

Answer 3

– along a diffusion gradient
– mass transport
– the ends of the tracheoles are filled with water

Question 4

what are the important parts of the insect exchange system?

Answer 4

– spiracles
– tracheas
– tracheoles
– fluid-filled ends of tracheoles

Question 5

what are the important structure of the gills?

Answer 5

– gill filaments - stacked
– gill lamellae
– counter-current flow
– gill bar

Question 6

what is the counter-current flow?

Answer 6

blood and water flow in opposite directions over the gill lamellae

Question 7

what does the arrangement of the counter-current flow mean?

Answer 7

– diffusion of oxygen from water to blood takes place as blood that is already loaded with oxygen meets water
– blood with little oxygen in meets water which has has most of oxygen removed.

Question 8

how is gas exchange in plants similar to insects?

Answer 8

– no living cell is far from the external air
– diffusion takes place in the gas phase

Question 8

what are stomata?

Answer 8

minute pores that occur mainly on leaves mainly on the underside.

Question 8

what are the adaptations for rapid diffusion in leaves?

Answer 8

– many small stomata
– numerous interconnecting air-spaces
– large SA

Question 8

what adaptations do insects have to reduce water loss?

Answer 8

– small surface area to volume ratio
– waterproof coverings over body
– spiracles can be closed

Question 8

In what ways are plants adapted to reduce water loss?

Answer 8

– a thick cuticle so a waterproof barrier
– rolling up of leaves so protects lower epidermis
– hairy leaves so traps still moist air
– stomata in pits or grooves so trap still moist air
– a reduced SA to V ratio of leaves

Question 8

describe the process of expiration

Answer 8

– internal intercostal muscles contract, external intercostal muscles relax
– ribs move downwards and inwards, decr volume of thorax
– diaphragm muscles relax so pushed up, volume of thorax further decreased
– increased pressure in lungs
– pulmonary pressure is higher so air forced out of lungs

Question 8

why are human lungs located inside the body?

Answer 8

– air is not dense enough to support and protect these delicate structures
– the body as a whole would otherwise lose a great deal of water and dry out

Question 8

what are the main parts of the human gas-exchange system?

Answer 8

– the lungs
– the trachea
– the bronchi
– the bronchioles
– the alveoli

Question 8

– what are the three sets of muscles that are used to creates pressure changes in the lungs?

Answer 8

– diaphragm
– internal intercostal muscles
– external intercostal muscles

Question 9

why would diffusion of gases between the alveoli and blood be rapid?

Answer 9

– red blood cells are slowed as they pass through pulmonary capillaries
– the distance between the alveolar air and red blood cells is reduced as rbc are flattened against capillary walls
– walls of alveoli and capillaries are very thin
– large SA

Question 9

describe the process of inspiration

Answer 9

– external intercostal muscles contract, internal intercostal muscles relax
– ribs are pulled upwards and outwards ( increase volume of thorax)
– diaphragm contract, flattens (incr volume of thorax)
– incr volume of thorax means less pressure
– atmospheric pressure now higher so air is forced in

Question 10

what are the main parts of the digestive system?

Answer 10

– the oesophagus caries food from the mouth to the stomach
– stomach - store and digest food
– ileum - digest food
– large intestine absorbs water
– rectum - stores faeces
– salivary glands - near mouth
– pancreas - large gland

Question 11

what are the two main stages of digestion?

Answer 11

1. physical breakdown
2. chemical digestion

Question 12

Describe the physical breakdown of food

Answer 12

– teeth break food down smaller
– food churned by muscles in the stomach

Question 13

Describe chemical digestion

Answer 13

– enzymes
– carbohydrase
– lipase
– protease

Question 14

describe the process of carbohydrate digestion in humans

Answer 14

– saliva enters moth
– salivary amylase
– acid in stomach denatures the amylase
– food passes into the small intestine
– pancreatic amylase
–epithelial cells in ileum produce maltase further break down

Question 15

what are the three most important peptidase?

Answer 15

– endopeptidase
– exopeptidase
– dipeptidase

Question 16

How are villi useful?

Answer 16

— they increase the surface area for diffusion — thin walled reducing diffusion distance — contain muscle so can move — well supplied with blood vessels — epithelial cells lining villi presses microvilli

Question 17

how are amino acids and monosaccharides absorbed?

Answer 17

Diffusion and co-transport

Question 18

How are triglycerides absorbed?

Answer 18

— lipid droplet broken down into micelles by monoglycerides and fatty acids in combination with bile salts — further broken down into monoglycerides and fatty acids — in epithelial cell triglycerides are then reformed.