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Combined Science GCSE > Biology: key concepts > Flashcards

Biology: key concepts Flashcards

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1
Q

What are all living things made of?

A

Cells

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2
Q

What two types can cells be?

A

Eukaryotic or prokaryotic

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3
Q

How can you tell if a cell is eukaryotic?

A

Has a nucleus

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4
Q

How can you tell if a cell is prokaryotic?

A

Has no nucleus

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5
Q

What are eukaryotes?

A

Organisms made up of eukaryotic cells

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6
Q

What is a prokaryote?

A

A prokaryotic cell (single-called organism)

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7
Q

What are the insides of a cell called?

A

Sub cellular structures

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8
Q

What is the function of a nucleus?

A

Contains genetic material arranged in chromosomes that controls activities of the cell

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9
Q

What is the function of a cytoplasm?

A

Gel-like substance where most chemical reactions happen. Contains enzymes which control chemical reactions.

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10
Q

What is the function of a cell membrane?

A

Holds cell together, controls what goes in and out

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11
Q

What is the function of a mitochondria?

A

Where most of the reactions for respiration take place, respiration transfers energy

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12
Q

What is the function of a ribosomes?

A

Involve in the translation of genetic material in the synthesis of proteins

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13
Q

Name the 5 parts of an animal cell

A

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

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14
Q

What is the function of a rigid cell wall?

A

Made of cellulose, supports and strengthens cell

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15
Q

What is the function of a large vacuole?

A

Contains cell sap, a weak solution of sugar and salts. Maintains the internal pressure to support the cell

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16
Q

What is the function of a chloroplast?

A

Contains chlorophyll. Where photosynthesis occurs, makes food for he plant.

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17
Q

What are the 8 parts of a plant cell?

A

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, cell wall, large vacuole, chloroplasts

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18
Q

What are the five sub cellular structures of a bacteria cell?

A

Ribosomes, cell membrane, plasmid DNA, chromosomal DNA, flagellum

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19
Q

What is the function of a chromosomal DNA?

A

One long circular chromosome, controls cells activities and replication, floats free in the cytoplasm

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20
Q

What is the function of a plasmid DNA?

A

Small loops of extra DNA, contains genes for things like drug resistance, can be passed between bacteria

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21
Q

What is the function of a flagellum?

A

Rotate to make bacteria move, away from harmful things, towards useful things

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22
Q

What does it mean if a cell is specialised?

A

It has adapted to a specific function

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23
Q

What are egg and sperm cells specialised for?

A

Reproduction

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24
Q

What type of nucleus do egg and sperm cells have?

A

Haploid (half the number of chromosomes in a normal body cell)

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25
Q

What are three main ways an egg cell is specialised?

A

It contains nutrients in the cytoplasm to feed the embryoIt has a haploid nucleus
Straight after fertilisation membrane hardens to stop more sperm getting in

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26
Q

What are four main ways an sperm cell is specialised?

A

Has long tail to swim to the egg
Has lots of mitochondria to provide energy (from respiration)
Has an acrosome at front of ‘head’, where it stores enzymes to ‘digest’ through egg cell membrane
Contains haploid nucleus

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27
Q

What is the function of Epithelial cells?

A

Line the surface of organs

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28
Q

How are ciliated epithelial cells specialised?

A

Specialised for moving materials. Have cilia (hair like structures) on top surface of cell. Cilia beat to move substance in one direction, along surface if the tissue.

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29
Q

Give an example of ciliated epithelial cells being used

A

Lining of airways contains lots of ciliated epithelial cells, help move mucus up throat away from the lungs

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30
Q

What do microscopes use to magnify images?

A

Lenses

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31
Q

What do microscopes do to an image?

A

Magnify + increase resolution

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32
Q

What does resolution mean?

A

How well a microscope distinguishes between two points that are close together

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33
Q

If a resolution is high, what does this mean for the image?

A

It can be seen clearly, in more detail

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34
Q

When we’re light microscopes invented?

A

1590s

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35
Q

How do light microscopes work?

A

By passing light through the specimen.

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36
Q

When were electron microscopes invented?

A

1930s

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37
Q

How do electron microscopes work?

A

Passing electrons through the specimen

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38
Q

What can light microscopes do that electron microscopes can’t?

A

View living cells

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39
Q

What can electron microscopes do that light microscopes can’t?

A

See the internal structure of sub cellular structures

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40
Q

What are the 8 steps for viewing a specimen using a light microscope? (Practical)

A

1) take a thin slice of specimen (to let light through)
2) take clean slide, add one drop of water using Pipette, use tweezers to place specimen on slide (water secures in place)
3) add drop of stain to specimen (if specimen is transparent/colourless) - makes specimen easier to see
4) place cover slip at one end of specimen, hold at angle with mounted needle, carefully lower onto slide. Press down gently (to avoid air bubbles), clip slide to stage
5) select lowest-powered objective lens
6) use coarse adjustment knob to move stage up so slide is just underneath objective lens. Look down eyepiece, move stage downwards until specimen nearly focused
7) adjust focus with fine adjustment knob, until image clear. Position clear ruler on stage and use it to measure diameter of circular visible area - field of view
8) if need to see specimen with greater magnification, swap to high powered objective lens, refocus,recalculate FOV accordingly

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41
Q

What are the three steps to creating a scientific drawing of a specimen

A

Draw outlines of main features using clear, unbroken lines. No colouring/shading.

2) are sure drawing takes at least half of space available. All parts in proportion
3) label important features with straight lines not overlapping. Include magnification used + scale

42
Q

What is calculation for total magnification?

A

Eyepiece lens magnification x objective lens magnification

43
Q

What is the equation for working out magnification without knowing lenses used?

A

Magnification = image size/ actual size

44
Q

What can we say about the units for image size and actual size?

A

Need to be the same units

45
Q

Real size of specimen is 21.5nano meters. Image size is 9800nanometers. Estimate the magnification

A

Round to 1 significant figure

10000/20=x500

46
Q

Order from largest to smallest: Millimeter, Nanometer, picometre, micrometer

A

Millimetre, micrometer, Nanometer, picometre

47
Q

How do we convert one of the four mini measurements to the next one down?

A

x1000

48
Q

Millimeter in Standard Form?

A

X10^-3m

49
Q

Micrometer in Standard Form?

A

x10^-6m

50
Q

Nanometer in Standard Form?

A

X10-9m

51
Q

Picometer in Standard Form?

A

10^-12m

52
Q

What little letter symbol is Millimeter represented by?

A

mm

53
Q

What little letter symbol is micrometer represented by?

A

um

54
Q

What little letter symbol is Nanometer represented by?

A

nm

55
Q

What little letter symbol is picometer represented by?

A

pm

56
Q

A specimen is 5x10^-6m wide. Calculate the width of the image of the specimen under a magnification of x100. Give your answer in standard form.

A 
Rearrange magnification formula
Image size=magnification x real size
Fill in values you know
Image size = 100 x (5x10^-6m)
Write out values in full
=100x0.000005m
Carry our calculation then convert back to standard form
=0.0005m
=5x10^-4m
57
Q

What are enzymes?

A

Biological Catalysts produced by living things

58
Q

Why are enzymes so useful?

A

Reduce the need to raise temperatures to speed up reactions, which would speed up unwanted reactions.

59
Q

What two things do chemical reactions usually involve?

A

Things either being split apart or joined together

60
Q

What is the active site?

A

The part where the enzyme joins on to its substrate to catalyse the reaction

61
Q

What do enzymes have in relation to substrate

A

High specificity for their substrate

62
Q

What is a substrate?

A

The Molecule changed in the reaction

63
Q

Describe the lock and key mechanism

A

The substrate has to fit into the active site for the enzyme to work. If substrate doesn’t match the active sites shape, then the reaction won’t be catalysed

64
Q 
Enzyme|.     2 -
Activity |.   1 /.   \3
              |.    /.      \
              |\_\_\_\_\_\_\_\_\_\_\_\_\_\_
             Temperature

Describe what is happening at 1,2 and 3

A

1) rate of reaction increases as the temperature increases. As kinetic energy increases more collisions occur.
2) optimum temperature (best/highest rate of reaction)
3) enzyme denatured - active site has changed shape

65
Q 
Enzyme|.     2 -
Activity |.   1 /.   \3
              |.    /.      \
              |\_\_\_\_\_\_\_\_\_\_\_\_\_\_
             pH

Describe what is happening at 1,2 and 3

A

1) rate of reaction increases as pH increases
2) optimum pH: highest rate of reaction. Varies depending on enzyme.
3) enzyme denatured as pH is too high

66
Q 
Enzyme|.     2 --------
Activity |.   1 /.   
              |.    /.      
              |\_\_\_\_\_\_\_\_\_\_\_\_\_\_
             Substrate concentration

Describe what is happening at 1 and 2

A

1) rate of reaction increases as the enzyme concentration increases
2) rate of reaction stays constant - too much substrate, not enough enzyme

67
Q

8 steps of a practical to investigate how pH affects amylase activity

A

1) put a drop of iodine solution into every well or a spotting tile
2) place Bunsen burner on heat proof mat, and tripod and gauze over Bunsen. Put beaker of water on top of tripod and heat water to 35*C. Keep temp constant through experiment, use thermometer to measure
3) use syringe to add 3cm^3 amylase solution to 1cm^3 of buffer solution with ph5 in boiling tube. Use test tube holders and put boiling tube into beaker of water. Wait for 5 minutes.
4) use new syringe to add 3cm^3 of starch solution to boiling tube
5) mix contents of boiling tube and start Stop clock
6) use continuous sampling to record how long it takes for amylase to break down all the starch. Use dropping Pipette to take fresh sample from boiling tube every ten seconds and put a drop into a well. When iodine solution remains browny-orange, starch is not present.
7) repeat whole experiment with buffer solutions of different pH values to see how pH affects time taken for starch to be broken down
8) control and variables each time (e.g. Concentration and volume of amylase solution) for fair test

68
Q

What is rate?

A

A measure of how much something changes over time

69
Q

An experiment measures how much something changes over time. How do you calculate the rate of reaction?

A

Divide the ankh that it has changed by the time taken

70
Q

The enzyme catalase catalysed the breakdown of hydrogen peroxide into water and oxygen. During an investigation into the activity of catalase, 24cm^3 of oxygen was released in 50 seconds. Calculate the rate of the reaction. Write your answer in cm^3 s^-1

A

Amount of product formed = change = 24cm^3

Rate of reaction = change / time = 24cm^3 / 50s = 0.48cm^3 s^-1

71
Q

What is the si unit for rate?

A

s^-1

72
Q

What type of molecules are proteins, lipids and some carbohydrates?

A

Big molecules

73
Q

Why do some big molecules need to be broken down into their smaller components?

A

So they can be digested and used for growth and other life processes

74
Q

What happens to molecules in food we eat once they’re broken down by digestive enzymes?

A

They are broken into smaller, soluble molecules. These pass easily through the walls of the digestive system, allowing them to be absorbed into the bloodstream. They then pass into cells to be used in the body

75
Q

Plants store energy in the form of starch, a carbohydrate. How does a plant use this energy?

A

The enzymes break down the starch into smaller molecules (sugars) that can then be respired to transfer energy to be used by the cells

76
Q

What enzyme breaks down carbohydrates? Into what? Give an example of a carbohydrase, and state what it breaks down and what it’s broken down into

A

Carbohydrases convert carbohydrates into simple sugars.

Amylase is breaks down starch, into simple sugars

77
Q

What breaks down proteins? What are they broken down into?

A

Proteases break down proteins into amino acids

78
Q

What breaks down lipids? What are they broken down into?

A

Lipases break down lipids into glycerol and fatty acids

79
Q

What are enzymes used to synthesise?

A

Carbohydrates, proteins and lipids from their smaller components

80
Q

How is carbohydrate synthesised?

A

By joining together simple sugars

81
Q

What is glycogen synthase

A

An enzyme that joins together lots of chains for glucose molecules to make glycogen (a molecule used to store energy in animals)

82
Q

What is glycogen made of? Which enzyme is used to synthesise it?

A

Many glucose molecules. Glycogen synthase joins these chains of molecules together.

83
Q

How is proteins synthesised?

A

Joining amino acids together

84
Q

How is lipids synthesised?

A

From fatty acids and glycerol

85
Q

What is diffusion?

A

Net movement of particles from an area of higher concentration to an area of lower concentration

86
Q

Is diffusion moving up or down the concentration gradient?

A

Down

87
Q

What substances does diffusion happen in?

A

Liquids and gases

88
Q

What types of molecules can diffuse through a cell membrane?

A

Very small molecules, like glucose, amino acids, water and oxygen. Big molecules (starch, proteins) can’t fit through

89
Q

What is osmosis?

A

The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

90
Q

What is a partially permeabel membrane?

A

Membrane with small holes in it.

91
Q

How does osmosis effect a solute solution?

A

It makes it more dilute

92
Q

What is active transport?

A

The movement of particles across a membrane against a concentration gradient (from area of lower to an area of higher concentration) using energy transferred during respiration

93
Q

Give an example of how active transport works in the digestive system

A

Lower concentration of nutrients in the gut than in the blood, active transport allows nutrients to be taken into the blood to stop us starving.

94
Q

Give the 10 steps of Investigating Osmosis experiment/practical

A

1) prepare sucrose solutions of different concentrations ranging from pure water to very concentrated
2) .use cork borer to cut potato in same size pieces (about 1cm diameter)
3) divide potato cylinders into forums of three, use mass balance to measure mass of each group
4) place one group in each solution
5) leave cylinders in solution for 40 mins
6) remove cylinders and pat dry gently with paper towel, removing excess water, so measure of final masses is accurate
7) weigh each group again and record results
8) in experiment, you change concentration of of sucrose solution. Volume of solution, size of potato cylinders, type of potato use, amount of drying etc must be kept the same
9) calculate percentage change in mass for each group of cylinders before and after their time in sucrose
10) plot a graph and analyse results

95
Q

(Investigating Osmosis experiment) A group of cylinders weighed 13.2g at the start of the experiment. At the end they weighed 15.1g. Calculate percentage change in mass.

A

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

15.1-13.2/13.2x100=14.4%

Positive result = potato cylinder gained mass

96
Q

Formula for percentage change in mass

A

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

97
Q

You have a graph of results from the Investigating Osmosis practical. What can you say about water concentration in points above x axis?

A

Water concentration of sucrose solution is higher than in the cylinders.

98
Q

You have a graph of results from the Investigating Osmosis practical. What can you say about water concentration in point where curve crosses x axis?

A

Fluid inside cylinders and the sucrose solution are isotonic (have same water concentration?)

99
Q

What does isotonic mean?

A

Same water concentration

100
Q

What Will a graph showing results from Investigating Osmosis practical look like

A

X axis = concentration of sucrose solution. Starts at 0 on y axis
Y axis = % change in mass
Gentle curve, shallower at bottom of y axis

101
Q

You have a graph of results from the Investigating Osmosis practical. What can you say about water concentration in points below x axis?

A

Wate concentration of sucrose solutions is lower than in the cylinders

Combined Science GCSE (8 decks)

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