b3 Flashcards

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1
Q

what is a cell

A

the basic building blocks of living organisms

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2
Q

what is a tissue

A

group of cells with a similar structure and function

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3
Q

what is an organ

A

aggregations of tissues performing specific functions

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4
Q

organ system

A

group of organs that have been organised into a system which work together to form organisms

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5
Q

function of mouth in the digestive system

A

mechanical digestion happens.
teeth chew the food. also place where salivary amalyse is secreted which is an enzyme.

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6
Q

oesophagus in digestive system

A

connects mouth to the stomach, where food goes down after being swallowed

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7
Q

stomach in digestive system

A

has hydrochloric acid which kills bacteria in food and also provides the optimum pH for some enzymes to work in
has muscles that also mechanically digest food

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8
Q

small intestine

A

where absorbtion of digested food molecules into the blood happen. the illeum is long and lined with villi which increases the surface area

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9
Q

large intestine

A

absorbs water from remaining material to produce faeces

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10
Q

pancreas

A

produces the digestive enzymes

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11
Q

liver

A

produces bile to help with the digestion of lipids

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12
Q

gall bladder

A

stores bile and releases into small intestine when lipids need to be digested

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13
Q

what are enzymes?

A

biological catalysts that are made from proteins
- they speed up chemical reactions that happen in the body and are not used up

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14
Q

explain the lock and key theory

A

the substrate binds to the active site of the enzyme because the shape of the active site is complimentary to the shape of the enzyme.
this causes a chemical reaction to produce smaller molecules.

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15
Q

what does amalyse do

A

breaks down starch into glucose. secreted by small intestine, pancreas and salivary glands
site of digestion is small intestine and salivary glands

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16
Q

what do proteases do?

A

break down proteins into amino acids
secreted by pancreas, stomach and small intestine
site of digestion is small intestine and stomach

17
Q

what do lipases do?

A

break down lipids into fatty acids and glycerol
secreted by pancreas and small intestine
site of digestion is small intetine

18
Q

what are the products of digestion used for

A

to build new carbohydrates, lipids and proteins.
some glucose is used in respiration
amino acids are used t build proteins like antibodies and enzymes
products of lipid digestion are used to build cell membranes and hormones.

19
Q

function of bile

A

made in liver, stored in gall bladder
- it is alkaline so neutralises the stomach acid in small intestine, providing optimum pH for the digestion of lipids
- it also emulsifies the fat to form small droplets which increases the surface area so more area for the enzyme to act on
both of these increase the rate of fat breakdown by lipase

20
Q

test for reducing sugars

A

benedicts solution - heat the sample and add the reagant.
if it turns from blue to brick red, it is a positive test

21
Q

test for starch

A

add iodine to the food sample, if it changes from brown to blue-black, it is positive test

22
Q

test for lipids

A

add ethanol and a few drops of distilled water. if it turns cloudy, then it is positive test

23
Q

test for proteins

A

biuret test - if it changes colour from blue to lilac then protein is present

24
Q

how does temperature affect the rate of enzyme activity

A

work fastest at optimum temperature -> 37 degrees celcius in human body
too high temeratures leads to the bonds holding the enzyme together to be broken. this means that it loses it’s shape, therefore the shape of the active site is no longer complimentary to the shape of the substrate, so it cannot bind together.
too low temperatures means that the enzyme does not have enough kinetic energy so there are fewer frequent collisions so both enzymes and their substrates collide at a lower rate

25
Q

what happens when an enzyme is denatured

A

the shape of the active site is lost completely. substrates cannot fit into denatured enzymes as the specific shape of their active site has been lost

26
Q

effect of pH on enzyme activity

A

optimum pH is normally 7, but some have acidic optimum pH and some have alkaline optimum pH.
if the pH is too high or too low, the bonds that hold the amino acid chain together to make up the protein can be destroyed.
this will change the shape of the active site, so the substrate can no longer fit into it, reducing the rate of activity.

27
Q

describe an experiment to investigate effect of pH on rate of amalyse activity

A