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biology gcse > topic 1 - key concepts in biology > Flashcards

topic 1 - key concepts in biology Flashcards

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1
Q

what are the 2 types of cells?

A

prokaryotic and eukaryotic

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2
Q

what is a prokaryotic cell?

A

cell without a nucleus

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3
Q

what is a eukaryotic cell?

A

cell with a nucleus

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4
Q

what subcellular structures are in an animal cell?

A

nucleus, mitochondria, cytoplasm, cell membrane, ribosomes

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5
Q

what subcellular structures are in a plant cell?

A

nucleus, cell membrane, cell wall, chloroplasts, mitochondria, permanent vacuole, ribosomes, cytoplasm

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6
Q

what is the function of the nucleus?

A

controls cells genetic material

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7
Q

what is the function of the cytoplasm?

A

site of cellular reactions

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8
Q

what is the function of the cell membrane?

A

controls what enters and leaves the cell

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9
Q

what is the function of the mitochondria?

A

site of aerobic respiration and produces ATP

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10
Q

what is the function of the ribosomes?

A

joins amino acids for synthesis of proteins

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11
Q

what is the function of the cell wall?

A

protect and support cell (stop bursting during osomosis)

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12
Q

what is the cell wall made of?

A

cellulose

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13
Q

what does a permanent vacuole contain?

A

cell sap

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14
Q

what is the function of the permanent vacuole?

A

supports cell, maintains turgidity

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15
Q

what is the function of the chloroplasts?

A

site of photosynthesis

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16
Q

what subcellular structures are found in bacteria cells?

A

chromosomal DNA, plasmid DNA, cell membrane, ribosomes, flagella

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17
Q

how is genetic info stored in prokaryotes?

A

free in cell (chromosomal and plasmid DNA)

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18
Q

what are plasmids?

A

small, circular DNA molecules found in bacteria

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19
Q

what is the prokaryotic cell made of?

A

peptidoglycan

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20
Q

what is the function of the flagellum?

A

long, hair-like structure that rotates to make bacterium move

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21
Q

what is the function of the chromosomal DNA?

A

1 long circular chromosome which controls cells activities and replication

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22
Q

what is the function of the plasmid DNA?

A

small loops of extra DNA not apart of the chromosome. contain genes

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23
Q

how are egg cells specialised?

A
  • large store of nutrients in cytoplasm
  • haploid nucleus (23 chromosomes)
  • cell membrane changes structure after fertilisation - stops sperm entering
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24
Q

how are sperm cells specialised?

A
  • long tail
  • streamlined head
  • lots of mitochondria in cell for energy - carries digestive enzymes
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25
Q

how are ciliated epithelial cells specialised?

A

small hairs (cilia) which can sweep substances move

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26
Q

how can the total magnification of an image be calculated from lens powers?

A

total magnification = eyepiece lens magnification x objective lens magnification

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27
Q

how can the magnification of an image be calculated?

A

magnification = size of image / size of real object

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28
Q

how does a light microscope work?

A

light passes though 1 or more lens to produce enlarged image

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29
Q

what are the advantages of light microscopes?

A
  • inexpensive
  • easy to use
  • portable
  • observe broth dead and living specimen
30
Q

what are the disadvantages of light microscopes?

A

limited magnification and resolution

31
Q

how does an electron microscope work?

A

uses beams of electrons focused by magnets. hit fluorescent screen which emits light producing an image

32
Q

what is the advantage of electron microscopes?

A

higher magnification and resolution

33
Q

what are the disadvantages of electron microscopes?

A
  • expensive
  • only view dead specimens
  • no colour
34
Q

how do you view a specimen using a light microscope?

A
  • thin slice to let light through
  • put drop of water (pipette) on a slide to secure specimen in place
  • place specimen on slide, and place cover slip at an angle to prevent air bubbles
  • put the slip on the stage
    -set to lowest-powered objective lens
  • use coarse wheel to move stage up to just below the objective lens
  • use fine wheel to bring into focus
35
Q

how do you convert m into milli?

A

x 10^3

36
Q

how do you convert m into micro (um) ?

A

x 10^6

37
Q

how do you convert m into nano (nm) ?

A

x 10^9

38
Q

how do you convert m into pico (pm)?

A

x 10^12

39
Q

what are enzymes?

A

biological catalysts

40
Q

how do enzymes work?

A

lower activation energy

41
Q

what is the active site of an enzyme?

A

place on enzyme where substrate binds and reaction occurs

42
Q

why are enzymes described as having high specificity for their substrate?

A

only substrates with a specific, complementary shape can fit into an enzyme’s active site.

43
Q

describe the lock and key model

A
  1. substrate collides with the active site of an enzyme
  2. substrate binds, enzyme-substrate complex forms
  3. substrate converted to products
  4. products released from the active site which is now free to bind to another substrate
44
Q

what factors affect the rate of an enzyme controlled reaction?

A

temperature, pH, substrate concentration

45
Q

what happens to enzyme activity as temperature increases?

A

at first, enzyme activity increases with temperature, until the optimum is reached. enzymes and substrates gain more kinetic energy, increasing the likelihood of successful collisions. past the optimum, active site denatures and the substrate no longer fits.

46
Q

what happens to enzyme activity as pH increases?

A

at first, enzyme activity increases with pH, until the optimum is reached. past the optimum, the active site denatures and the substrate no longer fits.

47
Q

what happens to enzyme activity as substrate concentration increases?

A

at first, activity increases because there is a higher likelihood of a successful collision. however once all active sites are full, activity remains the same

48
Q

how can the rate of an enzyme-controlled reaction be calculated when given a value for time?

A

rate = 1/time

49
Q

what are the units for rate?

A

s ^-1

50
Q

how can you investigate the effect of PH on enzyme activity?

A
  • drop of iodine into every spot on a tile
  • heat beaker of water to 35 degrees and keep constant
  • add amylase solution and pH 5 buffer to boiling tube, heat in beaker for 5 minutes
  • add starch solution , mix and start stop clock.
  • every 10 seconds, take a sample and add to a drop, when iodine remains brown- yellow instead of blue-black, all the starch has been broken down.
  • stop the stop clock, record time and calculate rate before repeating with buffer solutions of a different pH
51
Q

why must large molecules be broken down into smaller molecules in the body?

A

too big to be absorbed across the surface of the gut wall and absorption into the bloodstream

52
Q

what enzymes break down carbohydrates?

A

carbohydrase

53
Q

what enzymes break down proteins?

A

protease

54
Q

what enzymes break down lipids?

A

lipase

55
Q

what is starch broken into?

A

simple sugars like glucose

56
Q

what are proteins broken into?

A

amino acids (polypeptides)

57
Q

what are lipids broken into?

A

fatty acids and glycerol

58
Q

what does glycogen synthase do?

A

joins chains of glucose molecules to make glycogen

59
Q

why are small molecules synthesised into larger molecules in the body?

A

used for storage or to build structures

60
Q

how can you test for sugars?

A

benedicts reagent test - brick red if positive
method:
-add the reagent to a sample, and heat in a water bath set to 75 degrees.
- if positive, a coloured precipitate will form
- higher concentration, more red

61
Q

how can you test for proteins?

A

biuret test - purple if positive
method:
- use Biuret reagent
- first need to add potassium hydroxide to make the solution alkaline

62
Q

how can you test for lipids/fats?

A

emulsion (ethanol) test - cloudy if positive
method:
- shake sample with ice-cold ethanol, then pour into water.

63
Q

how do you test for starch?

A

iodine test - blue/black if positive
method:
-add sample to iodine

64
Q

what is calorimetry?

A

method of measuring heat transfer during a chemical reaction

65
Q

how can you use calorimetry to find the amount of energy in food?

A

-burn food under a known volume of water
-find temperature change
-calculate using formula

66
Q

what is the formula for energy in food? (J)

A

mass of water (g) x temperature change of water x 42

67
Q

what is simple diffusion?

A

net movement of particles from an area of high concentration to an area of low concentration until equilibrium is reached

68
Q

what factors affect rate of diffusion?

A

temperature, surface area, concentration

69
Q

what is osmosis?

A

diffusion of water across a partially permeable membrane from a high to a low concentration

70
Q

what is active transport?

A

movement of molecules across a cell membrane from a low to a high conc. assisted by enzymes and requiring enzyme

71
Q

how is % change in mass calculated?

A

% change = (final mass - initial mass / initial mass) x 100

72
Q

how can you investigate osmosis?

A
  • use a cork borer to cut cylinders of potato (cut off skin). cut to same length
  • find the mass of each group
  • place one group in a different concentration of sucrose solution
  • leave cylinders for 40 minutes
  • remove and pat dry gently to remove excess water which could affect the weight
  • weigh each group again and record the results
  • calculate percentage change in mass
    -water gained = higher sucrose conc. in potato
  • water lost = lower sucrose conc. in potato
  • no change = same sucrose conc. in solution and potato

biology gcse (6 decks)

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