Additional Science Flashcards

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1
Q

Name the 4 cell features shared by both plant and animal

A

Cell membrane, cytoplasm, nucleus, mitochondria

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2
Q

Name the 3 cell features of only a plant cell

A

Cell wall, vacuole, chloroplasts

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3
Q

Describe the function of the cell membrane

A

Separates the content of the cell and its surroundings and controls the movement of substances in and out of the cell

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4
Q

Describe the function of cytoplasm

A

It is where many of the chemical reactions needed to carry out life processes take place and it also contains organelles

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5
Q

What is the nucleus?

A

An organelle that contains DNA, it also controls all the activities of the cell

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6
Q

What is mitochondria?

A

The organelle in which respiration occurs

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7
Q

What is the function of the cell wall

A

It is made of cellulose to support the cell and allow it to keep its shape

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8
Q

What is the vacuole?

A

A space in the cytoplasm that is filled with cell sap to help support the plant by keeping the cells rigid

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9
Q

What do chloroplasts do?

A

They contain chlorophyll that absorbs the light energy used in photosynthesis

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10
Q

When was the electron microscope invented?

A

1930s

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11
Q

What does the electron microscope do?

A

It uses beams of electrons to magnify specimens up to about 2000000 times

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12
Q

How did electron microscopes change our understanding of bacteria cells?

A

Because they showed that bacteria have two kinds of DNA

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13
Q

What is chromosomal DNA?

A

It is a giant loop of DNA that contains the majority the genetic material

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14
Q

What is plasmid DNA?

A

It’s smaller loops of DNA that carries extra information

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15
Q

What is the difference between a plant cell wall and a bacteria cell wall?

A

A bacteria cell wall isn’t made from cellulose and is more flexible

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16
Q

What is the function of flagella?

A

They are a long, whip-like structure that bacteria can use to move themselves

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17
Q

What do chromosomes contain?

A

Genetic information

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18
Q

What are chromosomes made from?

A

A chemical called DNA

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19
Q

What are genes?

A

Sections of DNA molecules that contain instructions for specific proteins used in the body

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20
Q

What is the double helix?

A

It is the two strands in the molecule of DNA that are coiled together

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21
Q

What are the two strands in the double helix linked together by?

A

Bases

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22
Q

Name the 4 bases

A

Adenine-Thymine

Cytosine-Guanine

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23
Q

What are the matching bases known as?

A

Complementary base pairs

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24
Q

What are the base pairs joined together by?

A

A weak hydrogen bond

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25
Q

The ‘back bone’ of DNA is made from what?

A

Sugar (deoxyribose) and phosphate

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26
Q

On which molecule do the bases join to?

A

The sugar

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27
Q

Describe the role of Wilkins and Franklin in the discovery of DNA

A

They were directing beams of X-Ray’s onto purified DNA and used photos to record how the molecule scattered the X-ray and then from this they could work out how the atoms were arranged

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28
Q

Describe the role of Watson and Crick in the discovery of DNA

A

They used the X-Ray photographs (given to them by Wilkins without Franklins permission) from Franklin and Wilkins to create a 3D model of DNA

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29
Q

Describe the human genome project

A

It was an international effort that involved scientists in 18 different countries and sharing the data they collected about the human genome

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30
Q

What did the scientists working on the HGP work out?

A

The sequence of the 3 billion base pairs that make up the human genome which then showed that everyone has 99.9% of DNA in common

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31
Q

Name 5 ways in which the knowledge of the human genome can help medical technologies

A

Improved testing for genetic disorders
Ways of finding genes that increase risk of certain diseases
New treatments and cures for disorders
Showing evolution as the genome changes over time
Personalised medicines

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32
Q

What is genetic engineering?

A

The process of removing a gene from one organism and inserting it into the DNA of another

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33
Q

Give an example of a way in which genetic engineering has been used

A

Scientists have inserted the gene for human insulin into plasmid DNA into bacteria so that the bacteria can produce insulin

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34
Q

What is the name given to organisms that have been genetically engineered?

A

Genetically modified organisms

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35
Q

Describe how the genetic modification from wild rice to golden rice is beneficial for humans

A

Golden rice make beta-carotene which is needed by humans to make vitamin A. A lack of Vitamin A can cause death and blindness

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36
Q

Why’re some people worried about the GM rice?

A

They worry that it will crossbreed with wild rice and contaminate its DNA and others worry that GM food may harm them

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37
Q

What are the advantages and disadvantages of herbicide resistant crops?

A

Advantages:
Reduces the amount of crop spraying needed by farmers
One large dose of herbicide than lots of small ones

Disadvantages:
Herbicide resistant plants
Loss of biodiversity

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38
Q

Name the advantages and disadvantages of insulin producing bacteria

A

It can be used by vegans
Supply doesn’t rely on animals anymore
Can be made in vast quantities
Can be made cheaply

Doesn’t suit everyone as there are slight differences

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39
Q

What are the two enzymes used in the genetic modification of bacteria to produce insulin

A

Cutting enzymes and sticking enzymes

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40
Q

What is a diploid cell?

A

A cell that contains 2 sets of the 23 chromosomes

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41
Q

What form of cell division occurs for growth or the repairing of damaged cells?

A

Mitosis

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42
Q

Describe the stages of mitosis

A

DNA replication occurs so that there are now 4 sets of the chromosomes rather than just 2, the cell then divides and each daughter cell gets one copy of each chromosome, making them identical to each other and the parent cell

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43
Q

What kind of reproduction is mitosis?

A

Asexual reproduction

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44
Q

Give two examples of asexual reproduction

A

Bacteria cells often just split in half
Some plants do this by making new plantlets which are initially attached to the, but then split off and grow on their own

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45
Q

What is the name of the other kind of reproduction (not asexual)?

A

Sexual reproductions

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46
Q

Describe the process of sexual reproduction

A

This requires two haploid (one set of chromosomes) gametes which fuse during fertilisation to form a diploid zygote which then develops into an embryo

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47
Q

What kind of cell division is needed to produce haploid gametes?

A

Meiosis

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48
Q

Name the differences between meiosis and mitosis

A

Meiosis has two cell divisions and thus produces four haploid daughter cells which aren’t genetically identical

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49
Q

Describe the stages of meiosis

A

DNA replication occurs in the diploid cell so that there are 4 copies of the chromosomes, the diploid divides in two and then in two again to form four haploid cells which aren’t genetically identical as each has different sections of the DNA

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50
Q

What is a clone?

A

Individuals that are genetically identical

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51
Q

Describe how plants can be cloned

A

You start with a cutting from the plant which can then be planted and will continue or grow (this is an example of asexual reproduction)

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52
Q

Describes the benefits of cloning

A

It is useful to make an organism with desirable characteristics
E.g. bulls who produce high quality calves, good sniffer dogs
Can produce individuals with GM traits such as cows who produce insulin in their milk

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53
Q

Describe the drawbacks of cloning

A

Very low success rate

Can grow orders more quickly and die younger

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54
Q

What are the stages of cloning a mammal?

A

Removal of diploid nucleus from body cell
Enucleation of egg cell
Insertion of diploid nucleus into enucleated cell
Stimulation to start mitotic division
Implantation into surrogate mother

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55
Q

What is a stem cell?

A

A cell that can differentiate into different types of cells

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56
Q

Why are embryonic stem cells more useful than adult stem cells?

A

Because embryonic can differentiate into any cell whereas an adult stem cell is limited to certain types

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57
Q

Why is the use of embryonic stem cells controversial?

A

Because in the process of extracting the stem cells, the embryo is killed

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58
Q

Describe how a bone marrow transplant works

A

The patients white blood cells are destroyed and adult stem cells from someone else are put into the patient to produce healthy white blood cells

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59
Q

Why do bone marrow transplants not always work?

A

Because the body may reject the new cells and destroy them

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60
Q

How could the problem of rejection be solved in bone marrow transplants?

A

Because they could take a skin cell from the person to create an embryo, the stem cells could then be used to produce cells that make white blood cells and the body would recognise these cells as their own

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61
Q

What is a drawback of embryonic stem cell use?

A

They could be used to create human clones

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62
Q

What does the base order on the DNA strand form?

A

The genetic code

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63
Q

What is the process of amino acid chains forming proteins?

A

Protein synthesis

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64
Q

Where does transcription occur? (In protein synthesis)

A

In the nucleus

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65
Q

Describe what happens in transcription during the process of protein synthesis

A

The DNA unzips and the complementary bases to the strand will link together forming a molecule of mRNA

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66
Q

What does mRNA stand for?

A

Messenger RNA

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67
Q

What are the differences between DNA and RNA?

A

RNA uses the base Uracil instead of thymine and only has one strand so is therefore small enough to move out of the nucleus into the cytoplasm

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68
Q

After the mRNA leaves the nucleus, where does it attach?

A

It attaches to a small structure called the ribosome

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69
Q

What is the role of the ribosome?

A

It moves from one end of the mRNA to the other and decodes the bases in groups of 3 (codons)

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70
Q

What is an amino acid connected to?

A

transfer RNA

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71
Q

What happens once the ribosome has decoded the mRNA?

A

The complementary tRNA will line up with the mRNA and releases the amino acid to join the chain

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72
Q

What happens once the amino acid has joined the chain?

A

The tRNA is released as the ribosome moves onto the next codon

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73
Q

What is a polypeptide?

A

The chain of amino acids

74
Q

What happens to the polypeptide once it’s complete?

A

It can twist, fold up and may link with others to form a protein

75
Q

What is a protein?

A

It is a sequence of amino acids

76
Q

Why do different proteins have different functions?

A

Because the different sequence results in a specific shape of molecule

77
Q

Enzymes are ____ to their reaction

A

Specific

78
Q

Why are enzymes specific to a reaction?

A

Because of their shape

79
Q

What is a mutation?

A

A change in the sequence bases in the genetic code

80
Q

Why are some mutations not harmful?

A

Because some code changes won’t effect the amino acid sequence so the protein shape isn’t affected

81
Q

What are enzymes sometimes referred to as?

A

Biological catalyst

82
Q

Why are enzymes so critical to cell survival?

A

Because without them, reactions will happen at a too slow rate

83
Q

Describe how digestion enzymes work?

A

They help large substances to break apart into smaller ones

84
Q

How can enzymes help protein synthesis?

A

They help smaller chemicals to join to make large ones

85
Q

Describe how DNA replication works

A

An enzyme will catalyse the splitting apart of the DNA strands and the complementary base pairs will pair up. A different enzyme will then catalyse the joining together of the new bases to make new strands

86
Q

Why are digestion enzymes used in laundry detergents?

A

To help digest food and other molecules that stain clothing

87
Q

Why do proteins, fats and carbohydrates need to be broken down in digestion?

A

They are too large to pass across cell membranes of the gut into the blood

88
Q

Describe how fungi digest food

A

They grow on and through the food, after the enzymes have digested the food, the molecules can then absorb through the cell walls

89
Q

What is he name of molecules that enzymes work on?

A

Substrate molecule

90
Q

Name 3 things that affect rate of reaction (in terms of enzymes)

A

Temperature
pH
Substrate concentration

91
Q

What do carbohydrases break down?

A

Carbohydrates

92
Q

What do proteases break down?

A

Proteins

93
Q

What is the lock and key hypothesis?

A

It says that the substrate molecule fits tightly into the hole of the active site

94
Q

What is the active site?

A

The place that the substrate fits into where the bonds are either broken or created to make the product molecule

95
Q

What does is mean to denature the active site?

A

To change the shape of it so much that the enzyme is no longer fit for purpose

96
Q

What two things can denature the active site?

A

pH and temperature

97
Q

How do cells gain energy to power processes?

A

Respiration

98
Q

What is the word equation for respiration?

A

Glucose + oxygen —> Carbon dioxide + Water

99
Q

What is a capillary,

A

A tiny blood vessel

100
Q

Describe how substances move between cells and capillaries

A

Through a process of diffusion

101
Q

How does the process of diffusion work?

A

Particles move from an area of high concentration to low concentration - down the concentration gradient

102
Q

Where does gas exchange occur?

A

Between the alveoli and the capillaries in the lungs

103
Q

Blood enters the lungs with a higher concentration of what?

A

Carbon dioxide

104
Q

Describe the net movement of carbon dioxide in gas exchange

A

It diffuses from the capillaries to the alveolus

105
Q

Describe the net movement of oxygen in gas exchange

A

The oxygen diffuses from the alveolus to the capillaries

106
Q

What is stroke volume?

A

The volume of blood pumped on each pump

107
Q

What is the cardiac output?

A

The volume of blood circulated in a given time

108
Q

What is the word equation for anaerobic respiration?

A

Glucose –> lactic acid

109
Q

What is the need for EPOC?

A

The oxygen is needed to break down the lactic acid and release energy for the other processes in cells

110
Q

Through which process do plants manufacture glucose?

A

Photosynthesis

111
Q

What is the word equation for photosynthesis?

A

Carbon dioxide + water —> glucose + oxygen

112
Q

Where does photosynthesis occur?

A

In the chloroplasts

113
Q

What is the light for photosynthesis absorbed by?

A

Chlorophyll in chloroplasts

114
Q

Why are leaves broad and flat?

A

To provide a large surface area for maximum light absorption

115
Q

What is the role of stomata?

A

They allow carbon dioxide into the leaf

116
Q

What other two gases diffuse in and out of the stomata?

A

Oxygen and water vapour

117
Q

What do the large air spaces in leaves provide?

A

A large surface area to volume ratio

118
Q

What is the importance of a large surface area to volume ratio?

A

It allows efficient gas exchange

119
Q

Name the 3 most common limiting factors of plant growth/photosynthesis

A

Light intensity
Co2 concentration
Temperature

120
Q

What kind of cells so the surface of roots have?

A

Root hair cells

121
Q

What adaptation do root hair cells have that make them useful?

A

They have a large surface area for substances to enter the root

122
Q

What is osmosis?

A

The process in which water molecules move from a high concentration to a low concentration across a partially permeable membrane

123
Q

What is it called when something absorbs particles against the concentration gradient?

A

Active transport

124
Q

What do the xylem tissues do?

A

They transport water and minerals and also support the plant

125
Q

What does the phloem tissue do?

A

They transport sucrose

126
Q

What is transpiration?

A

The process where a loss of water through evaporation causes a pull of water and dissolved minerals up through the xylem roots

127
Q

What is sampling?

A

Looking at a small portion of an area or population

128
Q

Why is random sampling likely to be representative of the whole area?

A

Because every point has an equal chance of being selected

129
Q

What is a pooter used for?

A

It is used to catch small invertebrates through an inlet tube by sucking sharply on a second tube connected to a container

130
Q

Where is a sweep net used?

A

In areas with long grass

131
Q

What is a pond net used for?

A

To sample aquatic habitats

132
Q

What are pitfall traps used for?

A

To capture animals that aren’t that active during the day as they can be left overnight

133
Q

What is a quadrat and what is it used for?

A

It is a square frame which is randomly placed in an area and the number of plant species found in the quadrat can be counted up, they can be used to estimate total population size

134
Q

What is systematic sampling?

A

A method of sampling where the samples are selected from the population at regular or systematic intervals

135
Q

What are fossils?

A

Preserved traces or remains of organisms that lived thousands or millions of years ago

136
Q

What is the fossil record?

A

The history of life on Earth as shown by fossils from different periods of time

137
Q

Give 3 reasons why there are gaps in the fossil record

A

Fossils don’t always form
Soft tissue decays
Many fossils are yet to be found

138
Q

How does the pentadactyl (five-fingered) limb prove evolution?

A

Because many organisms share the structure (with variations) which suggests we come from a common ancestor

139
Q

What is the meristem?

A

The area just behind the tip of roots and shoots where cells keep divided

140
Q

What happens after the cells have divided at the meristem?

A

They elongate

141
Q

What happens to the cells in the older meristem area?

A

They differentiate

142
Q

Why are animals different to plants (in regards to growth)

A

Because they stop growing when they’re an adult

143
Q

What are the four components of blood?

A

Plasma, red blood cells, white blood cells, platelets

144
Q

What is the role of plasma?

A

It transports substances such as Co2, food substances and hormones

145
Q

What is the role of red blood cells?

A

To transport oxygen to the rest of the body in the form of oxyhemoglobin

146
Q

Why does the shape of a red blood cell make it beneficial?

A

It’s a biconcave disc which allows for a large surface area so maximum oxygen can diffuse in and out

147
Q

What other adaptation does a red blood cell have?

A

It has no nucleus to make more room for haemoglobin

148
Q

What do white blood cells do?

A

Some make antibodies which are proteins that bind to micro organisms that cause disease and destroy them. Others surround and destroy any foreign cells that enter the body

149
Q

Describe the journey of blood beginning at the vena cava

A

Vena cava-Right Atrium-Valve-Right Ventricle-Pulmonary Artery-Pulmonary Vein-Left atrium-Valve-Left Ventricle-Aorta

150
Q

What is the difference between a typical artery and the pulmonary artery?

A

The pulmonary artery carries deoxygenated blood

151
Q

What’s the difference between a typical vein and the pulmonary vein?

A

Pulmonary vein carries oxygenated blood

152
Q

What are the three types of blood vessel?

A

Arteries
Capillaries
Veins

153
Q

Why do arteries have strong thick walls?

A

Because the blood has to be under high pressure to ensure it reaches all parts of the body

154
Q

Why do capillaries have such thin walls?

A

In order to allow for diffusion of substances

155
Q

Why are veins so wide with a thin muscle layer?

A

The blood flows relatively slowly under low pressure

156
Q

What is the alimentary canal?

A

A muscular tube that runs from mouth to anus

157
Q

Name the 9 stages/places in the alimentary canal

A

1) mouth 2) oesophagus 3) stomach 4) small intestine

5) pancreas 6) large intestine 7) anus 8) liver 9) gall bladder

158
Q

Describe what happens in the mouth

A

During chewing, the food is broken down to smaller pieces and the tongue helps to form the food into a ball (bolus). Saliva acts as a lubricant to allow ease of swallowing and also begins to break down carbohydrates

159
Q

What does the oesophagus do

A

The muscles contract in waves to squeeze the food down to the stomach - this is called peristalsis

160
Q

Describe what the stomach does

A

It churns up the food with juices (such as enzymes and acids) and turns the bolus into a thick paste

161
Q

What is the role of the small intestine?

A

It contains enzymes to break down food and contains small projections called villi which allow for absorption into capillaries

162
Q

What does the pancreas do?

A

Makes digestive enzymes and releases them in to the small intestine

163
Q

What is the anus for?

A

Passing undigested food

164
Q

What does the liver do?

A

It processes the digested food in the blood plasma (from the small intestine). It also makes bile

165
Q

What does the gall bladder do?

A

It stores bile and releases it into the small intestine when needed

166
Q

What kind of enzyme is amylase and what do it do?

A

It is a carbohydrase that breaks down starch into simpler sugars which can be broken down by other enzymes into glucose

167
Q

Where is amylase produced/present?

A

It is present in saliva. It is also made in pancreas and released into small intestine

168
Q

What type of enzyme is pepsin and trypsin and where do they work?

A

They are proteases. Pepsin is made in the stomach and works there and trypsin works in the small intestine

169
Q

What do lipases do?

A

They digest fats and break them down to fatty acids and glycerol

170
Q

What does bile do?

A

It emulsifies large globules of fat into tiny fat droplets suspended in a watery liquid so they are more easily digested

171
Q

Where is bile made and stored and why is it stored there?

A

Bile is made in the liver but stored in the gall bladder. The gall bladder makes it alkaline which helps it to neutralise stomach acid but also produces a slightly alkaline environment for the proteases to work it

172
Q

Why are the villi so efficient at absorption of food?

A

Because they make the small intestine have a large surface area and furthermore they have a network of capillaries in each villus which allows for efficient food absorption

173
Q

What is the problem with people with coeliac disease?

A

Villi is lost so food absorption is less efficient

174
Q

What is a functional food?

A

Foods which claim to make you healthier

175
Q

What do probiotics contain?

A

They contain love ‘friendly’ bacteria such as lactobacillus and bifidobacteria

176
Q

What do lactobacillus and bifidobacteria do?

A

They produce lactic acid in the gut

177
Q

What are plant stanol esters?

A

Oily substances found in plants

178
Q

Why are plant stanol esters beneficial?

A

They stop the small intestine from absorbing cholesterol (a substance linked to heart disease)

179
Q

What are prebiotics?

A

They are substances that can’t be digested

180
Q

What are prebiotics beneficial?

A

Because they act as food for the ‘beneficial’ bacteria in the gut

181
Q

What are oligosaccharides?

A

A common form of prebiotic which prevents recurrence of diarrhoea