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GCSE Biology - Paper 1 > SB1 - Key Concepts in Biology > Flashcards

SB1 - Key Concepts in Biology Flashcards

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1
Q

What are prokaryotic cells?

A

Small, simple cells without a nucleus

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2
Q

Give an example of a prokaryotic cell.

A

Bacteria

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3
Q

What are prokaryotes?

A

Single-celled prokaryotic organisms

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4
Q

What are eukaryotic cells?

A

A complex cell that contains a nucleus and other subcellular structures

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5
Q

Give an example of eukaryotic cells

A

Any animal or plant cell

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6
Q

What are eukaryotes?

A

Organisms that are made up of eukaryotic cells

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7
Q

What is contained within the nucleus of a eukaryotic cell?

A

Genetic material / DNA / Chromosomes

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8
Q

What is the role of the nucleus?

A

It controls the activities of the cell

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9
Q

Name the gel-like substance contained within the cell

A

Cytoplasm

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10
Q

What is the role of the cytoplasm?

A

It is where most chemical reactions happen

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11
Q

Name the subcellular structure that holds the cell together

A

The cell membrane

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12
Q

Give another role of the cell membrane

A

It controls what goes in and out of the cell

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13
Q

Name the subcellular structure where respiration takes place

A

Mitochondria

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14
Q

Which subcellular structures are involved in protein synthesis?

A

Ribosomes

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15
Q

Which stage of protein synthesis is ribosomes involved in?

A

The second stage (Translation)

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16
Q

Name three structures that plant cells usually have but animal cells do not

A

Cell wall, chloroplasts, large permanent vacuoles

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17
Q

Which plant subcellular structure is usually made from cellulose?

A

Cell wall

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18
Q

What is the function of the cell wall?

A

A rigid structure that supports and strengthens plant cells

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19
Q

Which plant subcellular structure contains cell sap?

A

Permanent vacuole

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20
Q

What is cell sap made from?

A

A weak solution of sugars and salts dissolved in water

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21
Q

What is the function of cell sap?

A

To maintain the internal pressure of a cell, to provide support

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22
Q

Which plant subcellular structure is only found in photosynthetic cells?

A

Chloroplasts

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23
Q

What chemical reaction takes place in the chloroplasts?

A

Photosynthesis

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24
Q

Name the green substance contained within chloroplasts

A

Chlorophyll

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25
Q

What is the function of chlorophyll?

A

To absorb the light energy needed for photosynthesis

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26
Q

Name the parts of a bacterial cell

A

A single circular strand of chromosomal DNA, cytoplasm, cell membrane, cell wall, plasmid DNA, flagellum, ribosomes

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27
Q

Name the part of a bacterial cell that controls the cells replication

A

Single circular strand of chromosomal DNA

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28
Q

Name the small loops of DNA found in many bacterial cells?

A

Plasmids

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29
Q

What type of information is contained within the plasmids?

A

Drug resistance

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30
Q

Name the part of some bacterial cells that rotates to make the cell move

A

Flagellum

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31
Q

Describe the flagellum

A

Long hair-like structures

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32
Q

Give two reasons why bacterial cells find it beneficial to have flagellum

A
  1. They can move towards areas of beneficial condition (e.g. those high in nutrients and oxygen)
  2. They can move away from areas of harmful conditions (e.g. chemicals, heat)
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33
Q

Fungal cells contain a nucleus, mitochondria, a cell membrane and a cell wall. What type of cell are fungal cells?

A

Eukaryotic

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34
Q

Give one way a fungal cell is similar to a plant cell and different to an animal cell

A

Fungal cells have a cell wall, like a plant cell, whilst animal cells do not have a cell wall

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35
Q

Explain why multicellular organisms contain many different types of cells

A

Each individual cell cannot carry out every life process so cells become specialised to do different jobs

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36
Q

What word is used to describe these different types of cells

A

Specialised

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37
Q

What is the structure of each type of cell related to?

A

Its specific function

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38
Q

Name the four types of animal cells that you need to know how their structure are linked to its specific function

A

Sperm cells, egg cells, small intestine cells and ciliated epithelial cells

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39
Q

Which cell is only found in males?

A

Sperm cells

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40
Q

Name four adaptations of sperm cells

A

Long tail / mitochondria concentrated area at base of tail / streamlined shape / acrosome / haploid nucleus of male DNA

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41
Q

Name the adaptation that propels sperm cells forward

A

The tail

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42
Q

Name the adaptation that provides the energy for sperm cells

A

Mitochondria concentrated area at base of tail

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43
Q

Name the adaptation that makes it easier for sperm cells to move

A

Streamlined shape

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44
Q

Name the part of a sperm cell that contains enzymes

A

Acrosome

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45
Q

What is the function of the enzymes found in sperm cells

A

To digest the cell membrane of the egg

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46
Q

Where is the acrosome found?

A

In the front tip of the head

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47
Q

What is the function of sperm cells?

A

To transport male DNA to the female DNA found in the egg

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48
Q

Which cell is only found in females?

A

Egg cells

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49
Q

Name three adaptations of egg cells

A
  1. High nutrient content
  2. Haploid nucleus / nucleus with only 23 chromosomes
  3. Cell membrane can change structure
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50
Q

Name one adaptation that both sperm cells and egg cells share

A

A haploid nucleus / nucleus with only 23 chromosomes

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51
Q

Explain why both sperm cells and egg cells have the adaptation of the haploid nucleus

A

To ensure that the resulting zygote has the correct number of chromosomes (46)

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52
Q

What adaptation happens straight after fertilisation?

A

The cell membrane changes structure

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53
Q

Explain why the cell membrane changes structure straight after fertilisation

A

To prevent any other sperm from entering the egg

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54
Q

Explain why egg cells are very large cells

A

They contain a large amount of nutrients in the cytoplasm to provide nourishment to the developing embryo

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55
Q

Name two functions of egg cells

A
  1. To carry the female DNA

2. To nourish the developing embryo

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56
Q

Name the two adaptations of egg cells that ensure a resulting embryo has the correct number of chromosomes

A
  1. Haploid nucleus

2. Membrane that changes structure after one sperm has entered

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57
Q

Which cell is found in the airways?

A

Ciliated cells

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58
Q

What is the main adaptation of ciliated cells?

A

Hair-like structures on the top surface of the cell

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59
Q

What is the function of the hair-like structures on the top surface of the cell?

A

To move substances in one direction along the surface of the tissue

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60
Q

Explain why ciliated cells contain a high number of mitochondria

A

To provide enough energy to move the cilia

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61
Q

Where in a female body are ciliated cells found?

A

Fallopian tubes / oviduct

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62
Q

What is the role of specialised cells found in the small intestine?

A

To absorb molecules through intestinal wall

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63
Q

Name the subcellular structures that increase the rate of the absorption of molecules through intestinal wall

A

Microvilli

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64
Q

Explain how the absorption of molecules through intestinal wall are adapted to their function

A

They increase the surface area of the cell

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65
Q

What is the study of very small objects?

A

Microscopy

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66
Q

Which piece of scientific equipment is used to study things that are too small to see with the naked eye?

A

Microscope

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67
Q

Name the first type of microscope

A

Light microscope

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68
Q

When was the first microscope developed?

A

1590’s

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69
Q

What can we see using a light microscope?

A

Individual cells and large subcellular structures

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70
Q

What is the maximum magnification of light microscopes?

A

X 1500

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71
Q

What is the maximum resolution (in mm) of light microscopes?

A

0.0001 mm

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72
Q

How would you write 0.0001 mm in standard from?

A

1 x 10^-4 m

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73
Q

How old you write 0.0001 mm in nanometers?

A

100 nm

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74
Q

How do light microscopes form an image?

A

Using light and lenses

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75
Q

Write one picometre in standard form

A

1 x 10^-12 m

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76
Q

Write one nanometre in standard from

A

1 x 10^-9 m

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77
Q

Write six micrometers in standard form

A

6 x 10^-6 m

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78
Q

Convert 6mm into nanometres

A

6,000,000 nm / 6 x 10^6 nm

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79
Q

Name the type of microscope that was developed in the 1930’s

A

Electron microscope

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80
Q

How does an electron microscope form an image?

A

Using beams of electrons passing through a specimen

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81
Q

What is the maximum resolution (in mm) of the electron microscope?

A

0.0000002 mm

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82
Q

What is the maximum magnification of an electron microscope?

A

X 2,000,000

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83
Q

Explain why an electron microscope has images that show more detail compared to a light microscope

A

They have a greater magnification and a greater resolution

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84
Q

When preparing a slide, what is first placed on a clean slide?

A

Drop of water

85
Q

Explain the function of the drop of water on a clean slide during the preparation of the slide

A

To secure the specimen in place

86
Q

Explain why a stain is usually added to a slide specimen

A

To add colour to objects in a cell so they are easier to see

87
Q

What stain would you use when preparing a slide of onion skin?

A

Iodine

88
Q

What stain would you use when preparing a slide of cheek cells?

A

Methyl blue

89
Q

Once a slide is prepared, where on the microscope is it placed?

A

On the stage

90
Q

What keeps the slide in place?

A

Clips

91
Q

Which objective lens should be chosen first?

A

The lowest magnification

92
Q

What part of the microscope would you use first to move the stage?

A

The coarse adjustment knob

93
Q

Where should the stage be placed before looking down the eye piece?

A

Just below the objective lens

94
Q

Which part of the microscope should be used to bring the image roughly into focus?

A

The coarse adjustment knob

95
Q

What direction should the coarse adjustment knob be moved into to bring the image roughly into focus?

A

Downwards

96
Q

What should be moved to bring the image into clear focus?

A

The fine adjustment knob

97
Q

What should you do if you want to see the image at a higher magnification?

A

Swap to a higher powered objective lens and refocus

98
Q

What is the equation for calculating magnification of a microscope?

A

Total magnification = eyepiece lens magnification x objective lens magnification

99
Q

Calculate the total magnification used when viewing a specimen through a x4 eyepiece lens and a x50 objective lens

A

4 x 50 = x200

100
Q

State the equation for calculating magnification if you do not know the power of the lenses used

A

Magnification = image size / real size

101
Q

If you have a specimen that is 2.5 x 10^-2 mm wide and the image is 10 mm wide, calculate the magnification of the microscope

A

Magnification = 10 / 0.025 (2.5 x 10^-2) = x 400

102
Q

An image of a cheek cell with a width of 60 um shows that the nucleus fits 8 times across the cell. Calculate the width of the nucleus

A

Width of nucleus = 60 / 8 = 7.5 um

103
Q

A mitochondrion measured using an electron microscope has a width of 4.8 um and a height of 1.5 um. Estimate the area of the mitochondria

A

4.8 x 1.5 = 7.2 um^2

104
Q

A ribosome with a width of 4 x 10^-5 mm is observed as being 900 um wide in an electron microscope image. Calculate the magnification of the image

A

Image size = 900 m / 1000 = 0.9mm

Magnification = 0.9 / 4 x 10^-5 = 0.9 / 0.00004 = x 22, 500

105
Q

Compare today’s light microscope with Hooke’s

A

Hooke’s microscope: contains a barrel with two lenses, uses light, magnification up to x 30, resolution down to 0.002 mm
Modern light microscope: contains a barrel with two lenses, uses light, magnification up to x 1500, resolution down to 0.0001 mm

106
Q

What do enzymes act as?

A

Biological catalysts

107
Q

Give the definition of a catalyst

A

A substance that speeds up a chemical reaction without being changed or used up itself

108
Q

What type of molecule are enzymes?

A

Proteins

109
Q

What gives each type of enzyme a unique shape?

A

The way the chain of amino acids folds up

110
Q

What is the model of enzyme action named?

A

The ‘lock and key’ model

111
Q

What are the molecules that interact with the enzyme called?

A

The substrate

112
Q

What is the uniquely shaped section of an enzyme called?

A

The active site

113
Q

What happens at the active site?

A

The substrate fits into the active site

114
Q

What does ‘high specificity’ for a substrate mean?

A

The enzyme will only interact with the specific substrate that matches the shape of its active site

115
Q

Explain why increasing temperature will usually increase the rate of an enzyme-catalysed reaction

A

The reactants have more energy, so they move around more and collide more often with enough energy for a reaction to take place

116
Q

Explain why enzymes will stop working if they get to hot (2 marks)

A
  1. Some bonds holding the protein structure of the enzyme in place will break and change the shape of the enzyme
  2. If the shape of the active site is changed it will stop working because the substrate will no longer fit into the active site
117
Q

What is the scientific term for an enzyme that no longer works?

A

Denatured

118
Q

What temperature do human enzymes work at?

A

37-38 degrees celsius

119
Q

At what temperature do most human enzymes stop working?

A

45 degrees celsius

120
Q

What is the definition of an enzyme’s optimum temperature?

A

The temperature at which the enzyme is most active

121
Q

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

A

The higher the substrate concentration, the faster the rate of reaction

122
Q

Explain why the higher the substrate concentration, the faster the rate of reaction

A

Higher the concentration, the more likely that the enzyme will collide with and interact with the substrate molecule

123
Q

When does the concentration of a substrate no longer affect the rate of reaction?

A

When the number of substrate molecules is greater than the number of enzyme active sites / when all the enzyme active sites are full

124
Q

How does pH affect an enzyme if it is too high or too low?

A

The pH affects the bonds holding the enzymes together therefore changing their shape at the active site. The enzyme becomes denatured

125
Q

When investigating the effect of pH on the action of the enzyme amylase, what equipment would you need?

A

Spotting tile, dropping pipette, iodine solution, (bunsen burner, tripod, gauze, heatproof mat / water bath), 250ml beaker, boiling tube, 5ml syringes, test tube holder, stopwatch

126
Q

Which piece of equipment is better at keeping the temperature of the amylase solution at a constant temperature compared to using a bunsen burner?

A

A water bath

127
Q

What chemicals are used during the investigation of the effect of pH on the action of the enzyme amylase?

A

Iodine solution, pH buffers (pH1 to pH12), starch solution, amylase solution

128
Q

How many times should the experiment on the effect of pH on the action of the enzyme amylase?

A

Three times

129
Q

Why is doing an experiment three times important?

A

To produce a more accurate average time after removing outliers

130
Q

How could the pH be accurately measured during the investigation of the effect of pH on the action of the enzyme amylase?

A

Using a pH meter

131
Q

Name the independent variable in the investigation of the effect of pH on the action of the enzyme amylase

A

pH of buffer solutions

132
Q

Name the dependent variable in the investigation of the effect of pH on the action of the enzyme amylase

A

Time taken for the starch to be digested / iodine solution to stay brown

133
Q

State the control variables used during the investigation of the effect of pH on the action of the enzyme amylase

A

Use same volume of amylase solution, pH buffer and starch solution; same concentration of amylase solution, starch solution and iodine solution; same temperature of water in beaker / water bath

134
Q

State the equation to calculate the rate of reaction of the enzyme used in the investigation of the effect of pH on the action of the enzyme amylase

A

Rate = 1000 / time

135
Q

At pH6, it takes amylase 90 seconds to digest a starch solution. Calculate the rate of reaction

A

Rate = 1000 / 90 = 11 s^-1

136
Q

State the equation used to calculate the rate of reaction of an enzyme

A

Rate = change / time

137
Q

An enzyme reaction produces 24 cm^3 of a gas over 50 seconds. Calculate the rate of reaction

A

Amount of product formed = change = 24 cm^3

Rate = 24 / 50 = 0.48 cm^3 / s^-1

138
Q

What is the function of the pH buffer in the investigation of the effect of pH on the cation of the enzyme amylase?

A

To maintain a constant pH throughout the reaction, therefore maintain constant conditions in the boiling tube

139
Q

Name three main groups of big biological molecules that are essential for life

A

Carbohydrates, proteins, lipids

140
Q

What do organisms need to do to use carbohydrates, proteins and lipids for life processes such as growth?

A

Break them down into their smaller components

141
Q

Name the type of enzyme that digests carbohydrates

A

Carbohydrases

142
Q

Name the type of enzyme that digests carbohydrates found in saliva

A

Amylase

143
Q

What big molecule is digested by amylase?

A

Starch

144
Q

What is starch broken down into?

A

Maltose and other simple sugars (e.g. glucose)

145
Q

Describe the molecules produced by digestion

A

Small and soluble

146
Q

Name the type of enzyme that digests proteins

A

Proteases

147
Q

Where are proteases found in the body?

A

In the stomach / gastric juices

148
Q

What are proteins broken down into when they are digested?

A

Amino acids

149
Q

Name the type of enzyme that digests lipids

A

Lipases

150
Q

What are lipids broken down into by lipases?

A

Three fatty acids and one glycerol

151
Q

Where are lipases and carbohydrases found together in the body?

A

Intestines

152
Q

In addition to breaking down molecules, name another function of enzymes in the body

A

Synthesis of new molecules

153
Q

Name the two groups of sugars that can be tested for

A

Reducing sugars (e.g. glucose) and non-reducing sugars (e.g. sucrose)

154
Q

Describe how you would prepare a solid food sample for testing its content of sugars, starch and proteins (4 marks)

A
  1. Break up food in a pestle and mortar
  2. Transfer the ground up food into a beaker and add some distilled water
  3. Stir the mixture vigorously
  4. Let mixture to settle and pipette out some of the liquid to use as the sample
155
Q

Name the test for reducing sugars

A

Benedict’s test

156
Q

What is a positive result for reducing sugars?

A

The solution changes from its normal blue colour to green, yellow to red. The higher the concentration of reducing sugar, the further the colour change goes

157
Q

Explain why the water bath is set at 75 degrees celsius for the test for reducing sugars

A

To speed up the rate of reaction and therefore any colour change

158
Q

Explain why each food sample should be heated for the same amount of time in the test for reducing sugars

A

So the results can be compared - to make it a fair test

159
Q

Name the test for starch

A

Iodine solution

160
Q

Describe a positive result for the food test for starch

A

In the presence of starch, iodine solution turns a blue / black colour

161
Q

What colour is a negative result for the test of starch?

A

Yellow / brown colour

162
Q

Name the test for proteins

A

Biuret test

163
Q

Name the two chemicals used to test food for protein

A

Potassium hydroxide and copper (II) sulfate solution

164
Q

Describe a positive result for protein in food

A

Colour changes from blue to purple / lilac / pink

165
Q

Describe a negative result for protein in food

A

The solution remains blue

166
Q

Name the test for lipids

A

Emulsion test

167
Q

How do you prepare a sample of solid food to be tested for lipids?

A

Grind it up in a pestle and mortar

168
Q

What substance is added to the food sample in a test tube?

A

Ethanol

169
Q

After shaking, what is added after ethanol?

A

Distilled water

170
Q

Describe a positive result for the emulsion test

A

Precipitate is seen as a milky emulsion

171
Q

Name the type of experiments that can be used to work out the energy in different foods

A

Calorimetry

172
Q

Some foods were burnt to find out how much energy they contained. Explain how this experiment shows how much energy a food contains (2 marks)

A

The higher the temperature rise of the water, the more energy is contained within the food

173
Q

State the equation to calculate the total amount of energy in the burned food

A

Energy in food (J) = mass of water (g) x temperature change of water (degrees celsius) x 4.2

174
Q

How do you calculate the energy per gram of food?

A

Divide the energy in the food by the mass of the food in grams

175
Q

Explain why it is important to divide the energy in the food by the mass of the food in grams

A

To be able to compare the results of each food because the food samples are not exactly the same mass

176
Q

Explain why the results from the experiment where you investigate some foods that were burnt and find out how much energy they contained are only an estimation

A

Energy is lost to the surroundings and the test tube instead of being transferred to the water

177
Q

How do substances pass into and out of cells?

A

Diffusion, osmosis and active transport

178
Q

How do smells spread?

A

Diffusion

179
Q

What is the definition of diffusion?

A

The gradual movement of particles from an area of higher concentration to an area of lower concentration

180
Q

What states of matter can be involved in diffusion?

A

Gases and liquids

181
Q

Cells have partially permeable membranes. What does this mean?

A

The membranes only let some molecules through but not others

182
Q

What type of molecules can move through partially permeable membranes?

A

Very small molecules

183
Q

Describe the movement of particles in fluids

A

Random

184
Q

If there is a higher concentration of oxygen inside a cell compared to the outside, describe the net movement of oxygen particles

A

Out of the cell

185
Q

What is the net movement of water molecules called?

A

Osmosis

186
Q

Give a definition for osmosis

A

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

187
Q

State the net movement of water molecules across a partially permeable membrane separating distilled water on one side and sucrose solution on the other side

A

From distilled water into the sucrose solution

188
Q

If a cell is short of water what happens to the concentration of the solution inside?

A

It becomes more concentrated

189
Q

If the cell that is short of water is surrounded by a more dilute solution, describe the net movement of water molecules

A

Into the cell

190
Q

What happens to cells that gain water by osmosis?

A

They expand

191
Q

What happens to animal cells that gain too much water?

A

They burst

192
Q

What happens to plant cells that gain too much water?

A

They become turgid

193
Q

State the name for the process where particles can move against a concentration gradient

A

Active transport

194
Q

Explain how cells can absorb ions from dilute solutions

A

Energy transferred from respiration is used to move ions from an area of lower concentration to an area of higher concentration / against a concentration gradient

195
Q

Name a plant cell that relies on the absorption of ions from dilute solutions to absorb minerals

A

Root hair cell

196
Q

Name an animal cell that relies on the absorption of ions from dilute solutions to absorb glucose

A

Small intestine epithelial cell

197
Q

Using three different concentrations of sucrose solution, describe how you could investigate their effect on parsnip cells (6 marks)

A
  1. Use a cork borer to cut a parsnip into the same sized pieces (e.g. 1cm x 2cm cylinders)
  2. Divide the cylinders into groups of three and use a balance to measure the mass of each group
  3. Place 100cm^3 of each sucrose solution into separate beakers and place a group of cylinders into each solution
  4. Leave the cylinders in the solutions for one hour
  5. Remove the cylinders and gently pat dry with paper towels
  6. Use the balance to measure the new mass of each group
198
Q

Name the independent variable in the experiment where you use three different concentrations of sucrose solution to investigate their effect on parsnip cells

A

The concentration of sucrose solutions

199
Q

Name the dependent variable in the experiment where you use three different concentrations of sucrose solution to investigate their effect on parsnip cells

A

The cylinder mass

200
Q

Name the control variables in the experiment where you use three different concentrations of sucrose solution to investigate their effect on parsnip cells

A

The volume of solution, the size of cylinders, the age and type of parsnips used, amount cylinders are dries, time cylinders are left in the sugar solutions

201
Q

State the equation to calculate percentage change in mass in the experiment where you use three different concentrations of sucrose solution to investigate their effect on parsnip cells

A

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

202
Q

A group of cylinders weighed 14.3g at the start of experiment and 17.4g at the end. Calculate the percentage change in mass

A

((17.4 - 14.3) / 14.3) x 100 = 22%

203
Q

How do you find the concentration of a parsnip cell after plotting the percentage change in mass against the concentration of sucrose solution?

A
  1. Draw a line of best fit

2. Find the point at which the line of best fit crosses the x axis

204
Q

Describe an adaptation of a fat cell

A

Large amount of fat stored in droplets in the cell

205
Q

Explain how red blood cells are specially adapted to carry oxygen around the body

A

No nucleus makes more room for haemoglobin which combines with oxygen

206
Q

Describe the special feature of muscle cells that allow them to contract

A

Contain proteins that contract to shorten the cell

207
Q

Describe how the cells that line the gut are specialised to absorb nutrients

A

Microvilli increase their surface area, contain mitochondria to provide energy for active transport

208
Q

Explain how nerve cells are adapted to their function

A

Long fibre that carries electrical impulses around the body, many short connections to link to other nerve cells, myelin sheath to insulate impulse as it travels along the axon

209
Q

Explain why differentiation is important for organisms

A

It allows different parts of the body to become specialised for different functions so each function can be carried out effectively

GCSE Biology - Paper 1 (5 decks)

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