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Biology GCSE > key concepts > Flashcards

key concepts Flashcards

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1
Q

prokaryote

A

organism made of one prokaryotic cell (single celled organism)

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2
Q

eukaryote

A

organism made of eukaryotic cells (multicellular organism)

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3
Q

cell membrane

A

holds cell together and controls what goes in and out of the cell

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4
Q

cytoplasm

A

gel like substance where most chemical reactions occur

contains enzymes which control these reactions

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5
Q

nucleus

A

contains genetic material

controls the cell’s activities

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6
Q

ribosomes

A

involved in protein synthesis, in translation

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7
Q

mitochondria

A

where most of the reactions for aerobic respiration occur, transferring energy for the cell to work

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8
Q

cell wall

A

made of ceullolose

supports and strengthens the cell

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9
Q

vacuole

A

contains cell sap ( a weak solution of sugar and salts)

maintains internal pressure to support the cell

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10
Q

chloroplasts

A

where photosynthesis occurs to make food

contains chlorophyll

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11
Q

chromosomal dna

A

one long circular chromosome which controls activities and replication
floats free in the cytoplasm

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12
Q

plasmid dna

A

small loops of extra dna containin genes for things like drug resistance that can be passed between bacteria

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13
Q

flagellum

A

long hair like structure that rotates to move the cell

away from toxins and towards beneficial things like nutrients

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14
Q

specialised cells

A

cells which have a structure which makes them adapted to their function

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15
Q

functions of the egg cell

A

to carry the female dna

to nourish the developing embryo in the early stages

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16
Q

adaptations of the egg cell (4)

A

contains nutrients in cytoplasm for embryo
relatively large (large target for sperm to swim to)
haploid nucleus
straight after fertilisation, the membrane changes structure to prevent more sperm from entering, ensuring that the offspring has the right amount of dna

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17
Q

function of a sperm cell

A

to transport the male dna to the female egg

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18
Q

adaptations of the sperm cell (4)

A

long tail to swim to the egg
lots of mitochondria in the middle section to have energy to swim to the egg
acrosome contains digestive enzymes to pentrate the egg’s membrane
haploid nucleus

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19
Q

enzyme

A

a biological catalyst that speeds up the rate of metabolic reactions

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20
Q

substrate

A

the molecule changed in the metabolic reaction

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21
Q

active site

A

the region where the substrate binds to the enzyme and is catalysed

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22
Q

what is the lock and key hypothesis

A

enzymes are highly specific for their substrate
if the substrate’s shape doesn’t match the shape of the active site, then the reaction won’t be catalysed

(the substrate fits into the enzyme like a key fits into a lock)

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23
Q

denaturisation

A

when an enzyme loses the specific shape of its active site, preventing the enzyme from functioning

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24
Q

what 3 factors affect enzyme activity

A

temperature
pH
substrate concentration

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25
Q

how does temperature affect enzyme activity

A

at first a higher temperature increases the rate of reaction because kinetic energy increases and there are more collisions
HOWEVER
if the temperature become too hot, some of the bonds holding the enzyme together will start to break down, changing the shape of the active site and denaturing it

26
Q

how does pH affect enzyme activity

A

if the pH is too high or too low then the enzyme will denature
the typical optimum pH is 7 but not always, a stomach enzyme may have an optimum pH of pH2

27
Q

how does substrate concentration affect enzyme activity

A

the higher the substrate concentration, the faster the reaction up to a point
as the enzyme is more likely to collide and react with a substrate molecule but after a point there are so many substrate molecules that al active sites are full and adding more has no effect

28
Q

how do you investigate how changing the pH affects the activity of amylase

A
  • place one spot of iodine into every well of a spotting tile
  • place bunsen burner on heatproof mat with a tripod and gauze and place a beaker of water on top - heating it to 35°C
  • add 3cm^3 of amylase solution to 1cm^3 of buffer solution with pH5 to a boiling tube which should then be place in the beaker and wait for 5 mins
  • add 3cm^3 of starch solution to the boiling tube and mix
  • start a stop clock
  • every 10 seconds take a fresh sample from the tube and place into a well
  • repeat the experiment with buffer solutions of different pHs
29
Q

rate (formula)

A

1000/time or 1/ time

30
Q

units of rate

A

s^-1 (per unit of time)

31
Q

role of digestive enzymes

A

break down food molecules into smaller, soluble molecules which can pass through the walls of the digestive system and be absorbed into the bloodstream

32
Q

how do plants store energy

A

plants store energy as starch which when needed can be broken down by enzymes to sugars and respired to produce energy

33
Q

what does carbohydrase do

A

breaks down simple carbohydrates into simple sugars

34
Q

what do proteases do

A

break down protein molecules into amino acids

35
Q

what do lipases do

A

break down lipids into glycerol and fatty acids

36
Q

synthesis

A

organisms are able to synthesise carbohydrates, proteins and lipids from their smaller components using enzyme catalysed synthesis reactions

37
Q

what is the test for reducing sugars

A

benedict’s reagent

38
Q

how to do the benedict’s test

A

add blue reagent to a sample and heat in a water bath to 75°C - if positive a coloured precipitate will form

39
Q

what colour will the precipitate be in benedict’s test

A

least sugar concentration - blue
highest sugar concentration - red
GRADIENT

40
Q

what is the test for proteins

A

biuret’s test

41
Q

how to do the biuret test

A

add a few drops of potassium hydroxide solution to make it alkaline
add some copper (II) sulfate solution

42
Q

what are the results of the biuret test

A 
if positive (protein is present) - purple
if negative (protein not present) - blue
43
Q

what is the test for lipids

A

emulsion test

44
Q

how to do the emulsion test

A

shake test substance with ethanol for a minute until it dissolves
pour this solution into water

45
Q

what are the results of the emulsion test

A

if present, there will be a milky emulsion as the lipid precipitates out
the more lipids present, the more noticeable the milky colour will be

46
Q

what is the test for starch

A

testing with iodine

47
Q

how to do the iodine test

A

add iodine solution to a test sample

48
Q

what are the results of the iodine test

A

if starch is present - sample turns blue-black

if starch is not present - sample remains browny-orange

49
Q

what is the process of calorimetry (5 stages)

A

1) weigh a small amount of food that will combust easily and skewer it on a mounted needle
2) add a set volume of water to a boiling tube that is held with a clamp
3) measure the temperature of the water
4) set fire to the food with a bunsen burner and hold immediately under the tube ; relight and repeat until it will no longer relight
5) measure the temperature of the water again

50
Q

energy in food formula

A

energy in food (J) = mass of water (g) x temperature change of water (°C) x 4.2

51
Q

energy per gram of food formula

A

energy per gram of food (J/g) = energy in food (J)
————————
mass of food (g)

52
Q

resolution

A

how well a microscope can distinguish between two points that are close together

53
Q

magnification

A

how many times bigger an object is

54
Q

total magnification (formula)

A

eyepiece lens magnification x objective lens magnification

55
Q

development of microscopes

A

light microscopes were first developed in the 16th century
they shone light though a specimen allowing us to observe cells and some organelles such as the nucleus
in the 1930s, electron microscopes were developed
they use electrons and have a greater magnification and resolution to allow us to see specimens in greater details

56
Q

describe how to view a specimen using a light microscope (8)

A

1) take a thin slice of specimen
2) place a drop fo water on a clean slide and place the specimen on top using a pair of tweezers, use a stain if needed
3) using a mounted needle lower a cover slip over the specimen leaving no air bubble
4) clip the slide to the stage
5) select the lowest power objective lens
6) use the coarse focusing knob to move the stage up to be close to the objective lens then lower until nearly in focus
7) use the fine focusing knob to adjust
8) measure the field of view using a clear ruler

57
Q

diffusion

A

the net movement of gas or liquid particles form an area of high concentration to an area of lower concentration

58
Q

active transport

A

the movement of particles across a membrane against the concentration gradient using energy

59
Q

osmosis

A

the net movement of WATER particles across a PARTIALLY PERMEABLE membrane from an area of high concentration to an area of low concentration

60
Q

describe the potato-sucrose-osmosis experiment

A
  • prepare sucrose solutions of different concentrations
  • use a cork borer to cute potato into similar sized pieces
  • group potato cylinders into threes and weigh using a mass balance
  • place one group in each solution and leave for at least 40 minutes
  • remove and pat dry and then reweigh each group
61
Q

percentage change formula

A

(final mass - initial mass / initial mass) x 100

62
Q

isotonic

A

the point where the fluid inside the sucrose solution and the potato cylinders

Biology GCSE (8 decks)

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