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Edexcel GCSE Biology > Key Concepts > Flashcards

Key Concepts Flashcards

1
Q

Eukaryotes

A

Complex cells with nuclei. (Plant/ animal cells & Protozoa)

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2
Q

Prokaryotes

A

Simple cells with no nuclei.(amoeba, yeast, red blood cells)

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3
Q

What do animal cells contain?

A

Nucleus, mitochondria, cell membrane, cytoplasm, lysosome, ribosomes, centrosome

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4
Q

What do plant cells contain?

A

Cell wall, cell membrane, ribosomes, nucleus, lysosome, mitochondria, vacuole, chloroplasts, cytoplasm

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5
Q

Function of nucleus

A

Contains genetic material and controls cell. Surrounded by nuclear membrane.

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6
Q

Function of cytoplasm

A

Gel where chemical reactions take place containing enzymes which control these.

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7
Q

Function of cell membrane

A

Permeable membrane controlling what goes in and out the cell.

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8
Q

Function of ribosomes

A

Carries out protein synthesis, converting amino acids into protein. Need electron microscope to see it.

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9
Q

Function of lysosome

A

Contains digestive enzymes to digest excess organelles, engulfed viruses or food particles.

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10
Q

Function of mitochondria

A

Carries out aerobic respiration to power cell.

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11
Q

Centrosome function

A

Regulates mitosis (2 microtubules)

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12
Q

Function of cell wall

A

Cellulose structure, supporting and strengthening plant cell.

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13
Q

Function of chloroplasts

A

Contain chlorophyll to carry out photo synthesis.

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14
Q

Vacuole function

A

Contains cell sap( weak solution of sugar and salts) to support cell and keep it turgid. Controls internal pressure to support the cell.

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15
Q

Tissue

A

Group of similar cells that work together to carry out a particular function. They can contain more than one cell type.

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16
Q

Organ

A

A group of different tissues that work together to perform a function.

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17
Q

Epithelial cell

A

Cells that line structures in the body

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18
Q

Ciliates epithelial cell

A

Epithelial cells with cilia

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19
Q

Purpose of microvilli

A

Absorb substances

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20
Q

Purpose of cilia

A

Sweep substances along

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21
Q

What do bacterium contain

A

Chromosomal dna, flagella, slime coat, cell wall, cell membrane, ribosomes, plasmid dna, cytoplasm

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22
Q

What are included in animal cells and not bacteria?

A

Nucleus and mitochondria

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23
Q

Function of slime coat

A

Stops it from drying out or being engulfed

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24
Q

Function of flagella

A

Propels it away from harmful substances like toxins and towards beneficial things like oxygen or nutrients.

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25
Q

Purpose of plasmid

A

Small loops of extra DNA, containing genes for things like drug resistance. Can be passed between bacteria.

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26
Q

Function of chromosomal dna

A

Controls the cell’s activities and replication, floats free in the cytoplasm.

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27
Q

Actual size

A

Image size/ magnification

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28
Q

Resolution

A

The smallest distance between two points that can be seen as 2 points.

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29
Q

What 2 lenses are there in a microscope?

A

Eyepiece and objective lens

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30
Q

Nano meters

A

10^-9

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31
Q

Micrometers

A

10^-6

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32
Q

Magnification of a light microscope

A

1500*

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33
Q

Magnification of an electron microscope

A

2million*

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34
Q

Specialised cell

A

Cells with a specific function/job.

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35
Q

Cilia function

A

To keep passageways clear from mucus/ foreign particles.

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36
Q

Cell differentiation

A

The process by which a cell changes to become specialised for its job.

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37
Q

Pluripotent

A

Can become almost any cell in a human organism

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38
Q

MULTIPOTENT

A

Can develop into more than one cell type.

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39
Q

Potency of adult stem cells and where they are found

A

MULTIPOTENT cells found in bone marrow, blood vessels, heart and liver.

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40
Q

Potency of embryonic stem cells and where they are found

A

Pluripotent cells found in embryos/zygotes

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41
Q

Zygote

A

Newly fertilised egg

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42
Q

Advantages of embryonic stem cells

A

Pluripotent.
Easy to remove.
Could be cloned from own cells.
Embryos used in research from clinics are unwanted and would be destroyed anyway.

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43
Q

Advantages of adult stem cells

A

MULTIPOTENT.
No ethical issues.
Won’t reject own.

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44
Q

Disadvantages of embryonic stem cells

A

Ethical issues (murder?)
Could lead to illegal cloning
Risk of rejection
Risk of cancer.

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45
Q

Disadvantages of adult stem cells.

A

Harder to source.
Limited tissue from which is found.
Risk of rejection and cancer.

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46
Q

Time period for when embryos should be destroyed

A

14 days

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47
Q

What does IVF stand for

A

In Vitro Fertilisation

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48
Q

Example of use of adult stem cells

A

Bone marrow stem cells can be used to replace faulty blood cells.

49
Q

Example of use of embryonic stem cell

A

Replace faulty cells in sick such as insulin production cells for diabetics and nerve cells for paralysed.

50
Q

Function of acrosome

A

Contain enzymes that digest through an egg cells membrane.

51
Q

Enzyme

A

A biological catalyst that speeds up chemical reactions of living processes while remaining chemically unchanged.

52
Q

The reactions that enzymes take part in

A

Metabolic reactions

53
Q

What are enzymes made of?

A

Proteins and chains of amino acids which are folded into unique shapes.

54
Q

Actual size

A

Image / magnification

MIA

55
Q

Resolution

A

The smallest distance between 2 points that can be distinguished as 2 points

56
Q

What are the purpose of the adjustment knobs on a microscope?

A

They bring the sample into focus by moving the stage/objective lens up or down.

57
Q

Describe the steps of magnifying.

A

Select a greater magnification on the objective lens and use the adjustment knobs to focus in again.

58
Q

Total magnification

A

Eyepiece lens magnification * objective lens magnification

59
Q

Where do substrates bind to? And what do they become?

A

They bind to an active site to become a product

60
Q

When do enzymes work best? What happens when you heat up a metabolic reaction?

A

In their optimum pH/ temp. If you heat it up, the rate of reaction increases until a fixed point with which it is denatured.

61
Q

Why do enzymes only speed up one reaction? What model shows this?

A

Because a substrate needs to be the correct shape to fit into the active site. When enzymes are denatured, their shape is changed due to breaking of the bonds holding the enzyme together so can’t bind to the substrate. A lock and key model shows this.

62
Q

How do you measure how fast a product appears from the enzyme?

A

Use CATALASE (catalyser of hydrogen peroxide break down) in a hydrogen peroxide boiling tube and attach a bung which leads to a measuring cylinder in water. Put the b tube in a water bath at a constant temp while recording the oxygen and hydrogen produced in the first minute.

63
Q

How do you measure how fast the substrate disappears?

How could you extend this to test the effects of pH on enzyme activity?

A

Drop amylase (catalyses starch to maltose) and starch solution from a water bath into a tray of iodine every ten seconds until starch is no longer detected and so no longer turns iodine black. Record the time it takes for the substrate to disappear. To extend this you could repeat each experiment with buffer solutions of different pH values.

64
Q

How does increasing the concentration of a substrate affect the rate of metabolic reaction?

A

It increases metabolic reaction up until a certain point in which all active sites are full.

65
Q

Why do starch, proteins and fats need to be digested?

A

Because they are too big to pass through the walls of the digestive system and are insoluble. They need to be broken down into smaller molecules like amino acids, glycerol and fatty acids that are soluble and so can pass through digestive walls. This means these molecules can be absorbed into the bloodstream and cells to be used for growth and other life processes.

66
Q

What is starch converted to?

A

Maltose (by amylase) and then glucose (by maltase)

67
Q

What is protein broken into?

A

Amino acids via protease

68
Q

What are lipids broken into?

A

Glycerol and fatty acids via lipase

69
Q

What are carbohydrates converted to?

A

Simple sugars (via carbohydrase)

70
Q

Biological molecules

A

Long, complex molecules made up of smaller, basic units. (Carbohydrates, lipids, proteins…etc)

71
Q

What are Carbohydrates made up of?

A

They contain simple sugars which are made up of carbon, hydrogen and oxygen. They are converted into glycogen and starch before being converted into maltose and glucose.

72
Q

What are proteins made up of?

A

Long chains of amino acids, containing nitrogen, carbon, hydrogen and oxygen.

73
Q

What are lipids made up of?

A

Fatty acids and glycerol which contain carbon, oxygen and hydrogen. Can be tested via emulsion tests in ethanol as they turn ethanol milky white.

74
Q

How do you make a food sample?

A

Using a pestle and mortar, break up the piece of food, dissolve it in distilled water and then filter it.

75
Q

What’s the Benedict’s test?

A

The test for glucose and reducing sugars. Leave 10 drops of Benedict’s solution in a 75°C water bath with 5cm^3 of food sample (end pointing away). It will turn from blue if Carbohydrates are present in low concentrations and red for high concentrations.

76
Q

What’s the test for starch?

A

Add drops of iodine to 5cm^3 of food sample and shake to mix. It will turn black in the presence of starch.

77
Q

What’s the biuret test?

A

Test for protein. Add potassium hydroxide (alkaline) and (bright blue) copper sulphate into a test tube together. It will turn PURPLE if protein is present.

78
Q

What’s the emulsion test?

A

Test for lipids. Shake the substance in a tube with ethanol until dissolves and then pour solutions in water. Lipids present will show up as a milky emulsion.

79
Q

Calorimetry

A

Simple experiment of burning food to see how much energy that it contains.

80
Q

Describe the process of calorimetry.

A

Dry food will be weighed and skewered on a mounted needle. A set volume of water will be added to a boiling tube, held on by a clamp. Starting temp will be recorded and the food will be lit by the Bunsen burner. Make sure the Bunsen burner isn’t near the water. Hold lit food under water till it’s extinguished. Relight and repeat until can’t be burnt anymore, measure end temp of water. (Unreliable as other energy may be transferred to surroundings. To make more accurate you can insulate the boiling tube to stop the heat from escaping.

81
Q

Food energy

A

Water mass * change in water temp * 4.2 (amount of energy needed to raise 1g of water by 1°C)

82
Q

Calorie

A

Specific heat capacity.

Water has a calorie of 4.2.

83
Q

Energy per gram

A

Food energy / food mass

84
Q

Diffusion

A

Passive, gradual net-movement of particles from an area of high concentration to lower concentration (Down the concentration gradient).
Eg: substances in and out of cells, perfume diffuses through room.
We use it in gas exchange.

85
Q

How do substances move in and out of cells.

A

Through cell membranes via diffusion, osmosis and active transport. Particles move about randomly so therefore go both ways. Overall there is a net movement from the lower concentration side in diffusion.

86
Q

Osmosis

A

Passive, net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration. Water molecules actually pass both ways because they move about randomly but have a net flow into the region of fewer water molecules. This dilutes the solution until the concentration is equal either side of the membrane.

87
Q

Partially permeable membrane

A

A membrane (eg cell) that only lets small molecules pass through them, excluding larger ones like sucrose.

88
Q

Tissue fluid

A

Fluid that surrounds cells in the body and is transferred from blood capillaries to supply cells with nutrients. Has a different concentration to inner-cell fluid meaning water moves either into or out of cells via osmosis.

89
Q

Turgid

A

Swollen, distended or congested

90
Q

Passive

A

Requiring no energy

91
Q

Active

A

Requires energy

92
Q

Active transport

A

The active movement of particles against a concentration gradient, requiring energy from respiration. (Used in root hair cells).

93
Q

When is active transport used in the body?

A

When there is a lower concentration of nutrients in the gut than in the blood, active transport allows nutrients to be taken into the blood so that we don’t starve. This requires energy from respiration.

94
Q

What 4 factors affect the movement of substances?

A

Surface area to volume ratio larger surface area to volume ratio = higher rate of transport) distance(shorter distance = faster transport), temperature (warmer = more energy= faster transport), concentration gradient (bigger difference in concentration= faster osmosis/diffusion)

95
Q

How do you investigate diffusion in a non living system?

A

Put PHENOLPHTHALEIN and sodium hydroxide in Agar jelly and put in hydrochloric acid. Wait for jelly to change from pink to colourless as the acid diffuses through the jelly and diffuses it.

96
Q

How do you investigate osmosis in a living system?

A

Cut up potatoes in identical pieces and put them in beakers of differing sugar solutions. Measure starting and finishing lengths. Only thing you should change is the sugar solution. The potatoes in high concentration will get smaller while the potatoes in low concentration will grow turgid.

97
Q

How do you investigate osmosis in a non living system?

A

Put visking tube over thistle funnel and pour sugar solution down glass tube. Put in beaker of water and record difference in volume of substance in visking tube. The visking tube is the partially permeable membrane.

98
Q

Haploid

A

Having half the normal number of chromosomes.

99
Q

Egg cell function

A

To carry female DNA and nourish the developing embryo in its early stages.

100
Q

Adaptations of an egg cell

A

Have nutrients in the cytoplasm that feed the embryo.
Its membrane restructures after fertilisation to prevent any other sperm cells getting in, this means that the zygote has the right amount of DNA.
It’s also haploid.

101
Q

Function of a sperm cell

A

To transport male DNA to the female’s egg.

102
Q

Adaptations of a sperm cell

A

Have long tail to swim to egg.
Have much mitochondria to provide energy for swimming.
Has an acrosome in its head to store enzymes needed to digest through the egg cell’s membrane.
Has a haploid nucleus.

103
Q

Total magnification

A

Eyepiece lens magnification * objective lens magnification

104
Q

When were light microscopes invented and how do they work?

A

They were invented in the 1590’s and work by passing light through the specimen.

105
Q

When were electron microscopes invented and how do they work? What did this mean for science?

A

Invented in 1930’s and work by passing electrons through specimens instead of light. They have a much higher resolution and magnification. This means that we now have a much deeper understanding of cells and sub cellular structures. We can now see ribosomes.

106
Q

Summary of how to use a light microscope

A

Put drop of water over thin slice of specimen and put on slide with a cover slip on top (no air bubbles) and clipped to the stage. Always select lowest power objective len first and use coarse adjustment knob to raise stage just underneath objective lens before lowering it down to focus w fine adjustment knob. Measure your FOV.

107
Q

When using microscopy, what should you put on your specimen if it’ colourless?

A

Add a stain to it.

108
Q

Why do you add water to a specimen before putting the cover slip on top in microscopy?

A

This secures the specimen.

109
Q

FOV

A

Field of view, this allows you to estimate actual size.

110
Q

What do you need to do to produce a scientific drawing of a specimen?

A 
Use a sharp pencil to draw outlines.
Have clear/unbroken lines.
Makes sure it takes up at least half of space.
Keep in proportion.
Label w straight, uncrossed lines.
Include scale and magnification.
111
Q

Rate of reaction

A

1000/time

Amount changed/ time taken

112
Q

What will happen to the pH of a solution when lipids are broken down?

A

The pH will be lowered as the lipids will be broken down into fatty ACIDS as well as glycerol…

113
Q

Glycogen

A

A molecule used to store energy in animals

114
Q

Why do some enzymes join molecules together?

A

This is because some organisms need to be able to synthesise Carbohydrates, proteins and lipids from smaller components.

115
Q

What enzyme synthesises glucose into glycogen?

A

Glycogen synthase

116
Q

How to destarch a leaf

A

Leave it in the dark for an extended period of time.

117
Q

Lipase use and where it’s made/ works

A

Breaks down lipids to fatty acids and glycerol.
Made in pancreas and small intestine.
Works in small intestine

118
Q

Protease use

Where it’s made and works

A

Breaks down proteins into amino acids.
Made in stomach,pancreas and small intestine.
Works in stomach and small intestine

119
Q

Amylase use

Where it’s made/ works

A

Converts starch into sugars.
Made in salivary glands, pancreas and small intestine.
Works in mouth and small intestine

Edexcel GCSE Biology (12 decks)

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