Biology Paper 1 Flashcards
1
Q
Are plant cells eukaryotic or prokaryotic cells?
A
Eukaryotic
2
Q
Are animal cells eukaryotic or prokaryotic cells?
A
Eukaryotic
3
Q
Are bacteria eukaryotic or prokaryotic cells?
A
Prokaryotic
4
Q
Which are smaller, bacterial or pant cells?
A
Bacterial cells
5
Q
How much more smaller are bacterial cells than animal cells?
A
100 times smaller
6
Q
Describe the difference in where the genetic material is located between an animal and bacterial cell.
A
In an animal cell the genetic material is enclosed in a nucleus, whereas in the bacteria it is NOT FOUND IN A NUCLEUS, but it floats freely in the cytoplasm as a single circular strand of DNA
7
Q
What are plasmids?
A
Small rings of DNA
8
Q
True or false? “Prokaryotic cells have a cell wall.”
A
True.
9
Q
Which are bigger; bacterial cells (prokaryotes) or eukaryotes?
A
Eukaryotes.
10
Q
True or false? “Prokaryotic cells have a nucleus.”
A
False.
11
Q
In what form is the genetic material in a prokaryotic cell?
A
A single DNA loop.
12
Q
Name five common parts of animal and plant cells.
A
Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
13
Q
Describe the function of the nucleus.
A
Controls the cells activities.
14
Q
Describe the function of the cytoplasm.
A
Gel-like substances where most of the chemical reactions happen.
15
Q
Describe the function of the cell membrane.
A
Controls the movement of substances into and out of the cell.
16
Q
Describe the function of the mitochondria.
A
Where aerobic respiration occurs to release energy from glucose.
17
Q
Describe the function of the ribosomes.
A
Protein synthesis.
18
Q
Describe the function of the chloroplasts.
A
The location of photosynthesis.
19
Q
State the three subcellular structures found in a plant cell that are not found in an animal cell.
A
Cell wall, permanent vacuole and chloroplasts.
20
Q
Which strong material is the cell wall of plants and algal cells made from?
A
Cellulose.
21
Q
Name the green pigment found in the chloroplast of plant cells.
A
Chlorophyll.
22
Q
Why are cells specialised?
A
To carry out a particular function
23
Q
Why do sperm cells contain lots of mitochondria?
A
To provide the energy needed to swim to an egg cell.
24
Q
Why do sperm carry enzymes in their head?
A
The enzymes digest through the egg cell membrane so they can reach the nucleus.
25
Why do nerve cells have branched endings?
They allow them to connect to many other nerve cells and form a network throughout the body.
26
Why do muscles cells contain lots of mitochondria?
Muscles contract which requires large amounts of energy, this energy is released from glucose in the mitochondria in a process called respiration.
27
How are root hair cells specialised for absorbing water?
They have a large surface area for absorbing water and mineral ions from the soil.
28
When do most types of animal cells differentiate?
At an early stage of their development.
29
What is differentiation?
It is the process by which cells become specialised.
30
When do plant cells differentiate?
Most types of plant cells differentiate throughout their entire life.
31
What is the main purpose of differentiation in mature animals.
Repair and replace cells.
32
Give an example of two cell types that need to be replaced regularly.
Skin and blood cells.
33
As a cell differentiates, why does it acquire different sub-cellular structures?
To enable it to carry out its particular function.
34
What are the two advantages of electron microscopes over light microscopes?
1. Increased magnification, 2. Increased resolution.
35
What is the “resolution” or “resolving power” of a microscope?
The ability to distinguish between two points.
36
What are the three forms of equation used to calculate magnification (M), the image size (I) or the actual size of an object (A)?
1. A=I/M, 2. I=A x M, 3. M=I/A
37
A specimen is 50 micrometres wide. Calculate the width of the image of the specimen under a magnification of x100. Give your answer in mm.
100 x 50 = 5000 micrometres, 5000micrometers = 5mm
38
What is 1340000 nm expressed in standard form?
1.34 x 106 nm
39
What do light microscopes use to form an image?
Light.
40
What do electron microscopes sue to form an image?
Electrons.
41
When using a microscope, which objective lens should a student use first? X4, x10, 40 or x100?
X4
42
Why should you use the smallest magnification object lens first, when viewing a specimen?
gives the largest field of view
or
easier to focus
43
The size of an image is 22mm. The magnification is x1000000. Calculate the real size of the cell in micrometres.
25 / 100000 = 0.00025mm, 0.00025mm = 0.25 micrometres
44
State three things you should do when drawing your observations from a microscope.
Drawing takes up half the page, draw with clear unbroken lines, use a sharp pencil, include a title, include the magnification, label the most important features, do not include colouring or shading
45
How has electron microscopy increased biologists' understanding of cells?
Allow us to study cells in much finer details
understand and see more sub-cellular structures
such as ribosomes and plasmids
and the internal structures of mitochondria and chloroplasts
46
Why is iodine normally added to a specimen slide?
Iodine is a stain
| easier to see the different parts of a cell
47
What material is found in the nucleus of cells?
Genetic material.
48
What are chromosomes?
Coiled up length of DNA molecules.
49
What are genes?
Small section of a chromosome that codes for the development of a characteristic / protein.
50
How many chromosomes are found in a normal human nucleus?
23 pairs or 46.
51
How many copies of each chromosome do we have?
2 copies.
52
Where do the copies of our chromosomes originate from?
One copy from our mother and the other copy from our father.
53
What happens during the three overall stages of the cell cycle?
1) Growth and DNA replication
2) Mitosis - complete set of chromosomes pulled to each end of the cell, two new nuclei form
3) Cytoplasm and cell membrane divide
54
What has to happen within the cell before it can divide? (2 steps)
1. Cell organelles (e.g. mitochondria and ribosomes) have to replicate, 2. DNA has to be replicated (copied).
55
How many chromosomes will be present in a cell after DNA replication?
92 OR 46 pairs.
56
What is the main purpose of mitosis in multicellular organisms?
Growth and development.
57
In mitosis where do the chromosomes line up before being pulled apart?
Line up at the centre of the cell.
58
How many daughter cells are made at the end of the cell cycle?
Two.
59
How would you describe the daughter cells produced at the end of the cell cycle in relation to the parent cell?
The daughter cells are identical to the parent cell.
60
Describe the shape of the chromosomes formed during DNA replication.
X shaped chromosome.
61
If a parent cell has 56 chromosomes and undergoes the cell cycle, how many chromosomes will the daughter cells have?
They will also have 56 chromosomes.
62
What is a stem cell?
An undifferentiated cell.
63
Define differentiation.
The process by which a cell becomes specialised.
64
Name the two sources of stem cells in humans.
1) Human embryos
| 2) Adult stem cells - bone marrow
65
Describe the main difference between stem cells found in human embryos and adult stem cells found in the bone marrow.
Embryonic stem cells can differentiate into MOST type of cells but adult stem cells cannot. Adult stem cells only differentiate into SOME types of cells such as blood cells.
66
Where are stem cells found in plants?
In the meristem.
67
What is a potential use of stem cells in medicine?
To treat conditions where cells have been damaged e.g. diabetes, paralysis.
68
What is therapeutic cloning?
An embryo is produced with the same genes as the patient.
69
Describe an advantage of using stem cells created from therapeutic cloning.
Less chance the cells are rejected by a patient, because they have the same genes.
70
Describe a risk involved in growing stem cells in a lab.
Stem cells may become infected with a virus which could be passed on to the patient.
71
Why might some people be against stem cell research?
1) They may see each embryo as a potential human life
| 2) They may have religious objections to the use of stem cells
72
State three advantages of using stem cells to produce identical plants.
1) Clones can be produced quickly and cheaply.
2) They can be used to grow more rare species
3) Can be used to grow plants that have desired features such as diseases resistance.
73
Name the process by which oxygen moves into cells.
Diffusion.
74
Define "diffusion".
The net movement of particles from an area of high concentration to an area of low concentration.
75
State the three factors that affect the rate of diffusion.
1) Concentration gradient
2) Temperature
3) Surface area
76
How does temperature affect the rate of diffusion?
Increasing temperature increases the rate of diffusion
| Decreasing temperature decreases the rate of diffusion.
77
Does a single-celled organism have a higher or lower surface area:volume ratio compared to a multicellular organism?
Higher.
78
An organism has a surface area of 50m2 and a volume of 20m3. What is its surface area to volume ratio?
2.5:1
79
Why do multicellular organisms tend to need exchange surfaces and transport systems?
Low SA:vol, therefore cannot rely on diffusion across cell membranes.
80
How does the concentration gradient affect the rate of diffusion?
The higher the concentration gradient the faster the rate of diffusion.
81
State the states of matter that diffusion can be applicable to.
Liquids and gases.
82
Can diffusion happen in solids?
No
83
How are the small intestines adapted for exchanging materials?
1) Covered in villi giving them a large surface area
2) Good blood supply
3) Single layer of surface cells - short diffusion pathway
84
How are the lungs in mammals adapted for exchanging materials?
1) Have many alveoli which provide a large surface area
2) Moist lining - allow the easy dissolving of gases
3) Alveoli walls are one cell thick - short diffusion pathway
4) Good blood supply
85
How are the leaves in plants adapted for exchanging materials?
1) Flattened shape of the leaf increases surface area for exchange
2) Underneath of the leaf contains small holes called stomata which allows gases to pass through
3) There are air spaces in the leaf to maximise exposed surface area
86
Define osmosis.
Osmosis is the net movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration.
87
What is a partially permeable membrane?
A membrane with small holes in it that allows small molecules like water to pass through but restricts large molecules like starch from passing through.
88
What happens to an animal cell that loses a lot of water?
It shrivels up.
89
What can happen to an animal cell that gains a large amount of water by osmosis?
The cell can burst.
90
What happens to a plant cell if it loses a lot of water?
It becomes plasmolysed (cell membrane shrinks away from the cell wall).
91
If a plant cell gains a lot of water, what happens?
It becomes turgid (cell membrane pushes up against the cell wall).
92
If a solution is isotonic to the cell, what does this mean?
It means the concentration of solutes in the solution outside the cell is the same as the internal concentration.
93
If a solution is hypertonic to the cell, what does this mean?
It means the concentration of solutes in the solution outside the cell is higher than the internal concentration.
94
If a solution is hypotonic to the cell, what does this mean?
It means the concentration of solutes in the solution outside the cell is lower than the internal concentration.
95
How would water move if a solution was hypotonic to a cell?
More water would move into the cell by osmosis.
96
How would water move if a solution was hypertonic to a cell?
More water would move out of the cell by osmosis.
97
Define active transport.
It is the movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.
98
If there is a low concentration of mineral ions in the soil and a high concentration of mineral ions in the roots, by which process are the minerals absorbed an why?
The minerals would be absorbed by active transport because the movement of mineral ions would be against a concentration gradient and so require energy.
99
What process the energy needed for active transport?
Respiration
100
Does osmosis require energy?
No
101
Does diffusion require energy?
No
102
Why does active transport require energy?
Substances are moved against a concentration gradient, this require energy.
103
Describe the difference between how water and mineral ions are taken up by the roots.
Water is taken up by osmosis, whereas mineral ions are taken up by active transport.
104
Epithelial cells in the small intestine absorb food molecules by diffusion and active transport. Why is it necessary to absorb some food molecules by active transport?
So that the food molecules can be absorbed against a concentration gradient.
105
Epithelial cells in the small intestine absorb food molecules. Suggest why contain a large number of mitochondria?
Respiration releases energy from glucose, this is needed for active transport.
106
What are the basic building blocks of all organisms?
Cells.
107
What is the definition of a cell?
The individual unit of an organism.
108
What is the definition of a tissue?
Cells of the same type working together to perform a specific function.
109
What is the definition of an organ?
A structure made from different tissue types to perform a specific function.
110
What is the definition of an organ system?
Multiple organs working together to perform a specific function.
111
Is the stomach a cell, tissue or organ?
An Organ.
112
Is blood a cell, tissue or organ?
Tissue.
113
What is the function of the mouth in digestion?
To mechanically break up food into smaller pieces to increase surface area.
114
What is the function of stomach acid?
To kill potentially pathogenic microorganisms in food (NOT to digest food).
To provide the optimum pH for enzymes to work at
115
What is the function of the small intestine?
To absorb carbohydrates, lipids, amino acids, vitamins and mineral ions from digested food.
116
What is the function of the large intestine?
To absorb water from digested food.
117
What is the function of the liver in digestion?
To produce bile, an emulsifying and neutralising substance.
118
What is the function of the gall bladder?
To store bile until it can be released into the small intestine.
119
What is an enzyme?
A protein which can catalyse a reaction (speed it up) without being used up itself.
120
What is a substrate?
A molecule or atom which is acted upon by an enzyme.
121
Name two environmental conditions that can change an enzyme’s active site.
1. pH (either higher or lower than optimum), 2. Higher than optimal temperature
122
Name where carbohydrase is made in the body.
Salivary glands, pancreas and small intestine.
123
What do carbohydrases break down and what is produced?
Carbohydrates to simple sugars (e.g. amylase breaks down starch to glucose).
124
Name where protease is made in the body.
Stomach, pancreas and small intestine.
125
What do proteases break down and what is produced?
Proteins to amino acids.
126
Name where lipase is made in the body.
Stomach, pancreas and small intestine.
127
What do lipases break down and what is produced?
Lipids (fats) to fatty acids and glycerol.
128
How does bile help the action of lipase? (2)
1. Provides alkaline conditions by neutralising acid from the stomach, 2. Emulsifies fat to form small droplets with a larger surface area.
129
What happens to the active site of an enzyme if the temperature is to high?
The active site changes shape and the enzyme becomes denatured.
130
What is the name of the model that describes the mechanism for how enzymes work on substrates?
Lock and Key model
131
What are the products of digestion used for?
To build new carbohydrates, lipids and proteins.
132
Why does food need to be digested?
To convert it into small soluble molecules that can be absorbed into the bloodstream.
133
Name the test used to test for reducing sugars
Benedict's test.
134
Name the test used to test for starch
Iodine.
135
Name the test used to test for proteins.
Biuret test.
136
Name the test used to test for lipids.
Ethanol or Sudan III test.
137
Describe the colour change for a positive test for proteins using the Biuret test.
Blue to pink or purple.
138
Describe the colour change for a positive test for reducing sugars using the Benedict's test.
Blue to green, yellow or brick-red.
139
Describe the colour change for a positive test for starch using the Iodine test.
Browny-orange to blue-black
140
What is the scientific name given to the windpipe.
The Trachea.
141
What is the name of the membrane that surrounds the lungs.
The pleural membrane.
142
What are the name of the small air sacs located at the end of the bronchioles in the lungs.
Alveoli.
143
What is the name of the gas that passes from the alveoli into the blood capillaries?
Oxygen.
144
What is the name of the gas that passes from the blood capillaries into the alveoli?
Carbon dioxide.
145
What type of circulatory system do humans have?
A double circulatory system.
146
Name the three components of the circulatory system.
The heart, blood vessels and blood.
147
Where does the right ventricle pump blood to, and is the blood oxygenated or deoxygenated?
Pumps deoxygenated blood to the lungs.
148
Where does the left ventricle pump blood to, and is the blood oxygenated or deoxygenated?
Pumps oxygenated blood to the rest of the body (excluding the lungs).
149
Which system transports substances around the body in the blood?
The circulatory system.
150
What tissue are the walls of the heart made from?
Muscle tissue.
151
Name the two types of chambers in the heart
Atria and ventricles.
152
Name the upper chambers of the heart?
Atria.
153
Name the lower chambers of the heart?
Ventricles.
154
Where do the atria force blood upon contraction?
To the ventricles.
155
What is the job of the heart valves?
To prevent backflow of blood in the heart.
156
Through which blood vessel does blood flow away from the heart?
Arteries.
157
Through which blood vessel does blood flow back into the heart?
Veins.
158
Name the blood vessel by which blood leaves to the rest of the body.
Aorta.
159
Name the blood vessel by which blood arrives back from the rest of the body.
Vena cava.
160
Name the blood vessel by which blood leaves the heart to the lungs.
Pulmonary artery.
161
Name the blood vessel by which blood leaves the lungs to go back to the heart.
Pulmonary vein.
162
Where are the pacemaker cells located in the heart?
In the walls of the right atrium.
163
What do the pacemaker cells in the heart do?
They control your resting heart rate.
164
Which blood vessels have thick walls containing muscle tissue and elastic fibres?
Arteries.
165
Which blood vessels have thin walls and contain valves?
Veins.
166
Why do capillaries have permeable walls?
To allow substances to diffuse through them.
167
Why are the walls of capillaries only one cell thick?
Short diffusion pathway to increase the rate of diffusion of substances.
168
Do arteries or veins have a larger lumen?
Veins.
169
Where are the lungs located?
The upper part of the body (thorax).
170
What bones protect the lungs?
Ribcage.
171
How are the lungs in mammals adapted for exchanging materials?
1) Have many alveoli which provide a large surface area
2) Moist lining - allow the easy dissolving of gases
3) Alveoli walls are one cell thick - short diffusion pathway
4) Good blood supply
172
What is the liquid part of blood called?
Plasma.
173
Name the four components of blood.
Red blood cells, white blood cells, platelets and plasma.
174
What do red blood cells transport?
Oxygen.
175
What do red blood cells lack that normal cells have?
A nucleus.
176
What do platelets do?
Help clot the blood at wound sites.
177
What is the role of white blood cells in the body?
Defend the body against microorganisms.
178
What is the name of the pigment found in red blood cells?
Haemoglobin.
179
In the lungs which gas binds to haemoglobin?
Oxygen.
180
Why do red blood cells not contain a nucleus?
To allow more room to carry oxygen.
181
Describe the shape of red blood cells.
Biconcave shape.
182
Name three things that are transported in the blood plasma.
Carbon dioxide, urea, hormones, proteins and antibodies.
183
What is produced when oxygen binds with haemoglobin?
Oxyhaemoglobin.
184
What are the coronary arteries?
Blood vessels that supply the heart muscle tissue.
185
What occurs in CHD and how does this effect the heart?
The coronary arteries become blocked with fatty deposits, narrowing them.
Reduces flow of blood to the heart, therefore reducing supply of oxygen.
Oxygen is needed for respiration - so less respiration occurs.
Leading to a heart attack
186
How do stents treat CHD?
Re-opens the blocked coronary artery, restoring blood flow.
187
How do statins treat CHD?
Decreases the blood concentration of cholesterol, which reduces build-up of fatty deposits in the coronary arteries.
188
State three disadvantages of taking statins.
1) Have to be taken regularly
2) Can cause side effects such as headaches
3) They don't have an instant effect
189
State two complications that can arise during or after surgery to implant stents.
1) Infection from surgery
| 2) Blood clot developing near the stent
190
Name two sources of replacement heart valves.
1. Mechanical.
| 2. Biological (e.g. pigs or sheep).
191
Why are faulty heart valves life-threatening?
Allows backflow of blood - leading to poor circulation.
192
Describe a treatment used in the case of total heart failure.
Heart transplant.
193
When would an artificial heart be used?
1. To allow the heart to rest and recover.
| 2. To keep the patient alive whilst they wait for a transplant.
194
State the main advantage in using an artificial heart over a donor heart.
An artificial heart is likely to be rejected by a person's immune system.
195
What is artificial blood.
It is a blood substitute usually a salt solution (saline)
196
If after being given artificial blood a person is not able to produce new blood cells quickly, what will the patient need?
A blood transfusion.
197
State two disadvantages of artificial hearts.
1) Blood doesn't flow as smoothly which can cause blood clots.
2) Parts of the heart could wear out or the electric motor could fail.
198
What is “health”?
The state of physical and mental well-being.
199
What are the two types of disease?
Communicable (caused by a pathogen) and non-communicable.
200
Name three factors, other than pathogens, which can influence health.
1. Diet
2. Stress
3. Life situations
201
How can severe physical ill health affect your mental heath?
It can lead to depression.
202
Which non-communicable diseases can viruses such as HPV trigger?
Cancer.
203
The hepatitis virus causes long-term infections in the liver, this increases the chance of developing which type of cancer?
Liver cancer.
204
What is a risk factor?
A factor linked to an increased rate of disease.
205
Give two general examples of a risk factor.
1. The lifestyle of a person
| 2. Substances in the person’s body or environment
206
State a risk factor for diabetes.
Obesity.
207
State a risk factor for cardiovascular disease.
1) Poor diet
2) Smoking
3) Lack of exercise
208
State a risk factor for liver disease.
Alcohol consumption.
209
State a risk factor for lung cancer.
Smoking.
210
What is cancer?
The uncontrolled growth and division of cells.
211
What is a benign tumour?
A growth of abnormal cells which is contained in one area within the body and will not invade other body parts.
212
What is a malignant tumour?
A growth of abnormal cells which invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours.
213
Which type of tumour is cancerous?
Malignant tumours.
214
Which type of tumour is more dangerous and can be fatal.
Malignant tumours.
215
Name a risk factor for lung cancer.
Smoking.
216
Name a risk factor for skin cancer.
Excessive UV exposure.
217
Name a risk factor for breast and ovarian cancer.
Inheriting faulty gene.
218
Which type of tumour is localised and does not spread?
Benign tumours.
219
Name six plant tissues.
Epidermal, palisade mesophyll, spongy mesophyll, xylem, phloem, meristem.
220
Is the leaf a cell, tissue or organ?
Organ.
221
What is the epidermal tissue in a plant?
The tissue that covers the whole plant.
222
What process mostly happens in the palisade mesophyll tissue?
Photosynthesis.
223
Describe how the structure of the spongy mesophyll tissue is related to its function.
It contains large air spaces that allow for the diffusion of gases into and out of cells.
224
Why is the upper epidermis transparent?
So light can pass through it to reach the palisade layer.
225
How does the structure of the upper epidermis reduce water loss by evaporation?
It is covered in a waxy cuticle.
226
What are the names of the holes in the lower epidermis?
Stomata.
227
What cells control the opening and closing of the stomata?
Guard cells.
228
Which gas diffuses into the leaf through the stomata?
Carbon dioxide.
229
Name four factors which affect the rate of transpiration in plants.
1. Temperature
2. Humidity
3. Air movement
4. Light intensity
230
What is translocation?
The movement of sugars from the leaves to the rest of the plant through the phloem.
231
What is transpiration?
The movement of water from the roots to the leaves through the xylem, eventually leaving the leaves via evaporation.
232
What is the function of the xylem?
Transport water and mineral ions from the roots to the rest of the plant
233
What is the function of the phloem?
Transport dissolved sugars from the leaves to the rest of the plant
234
What effect does temperature have on the rate of transpiration?
Higher temperatures increase the rate of transpiration
235
What effect does humidity have on the rate of transpiration?
Higher levels of humidity decrease the rate of transpiration
236
Why does increased light intensity increase the rate of transpiration?
Stomata open wider to let more carbon dioxide into the leaf for photosynthesis
237
Describe the structure of phloem tissue.
Made of columns of elongated living cells with small pores in the end walls.
238
Describe the structure of xylem tissue.
Made of dead cells joined end to end with no end walls between them.
They are strengthened with a material called lignin.
239
What equipment can you use to estimate the rate of transpiration?
A potometer.
240
During what time of day the stomata close?
At night?
241
What happens to the guard cells and the stomata when the plant is short of water?
The guard cells become flaccid making the stomata close.
242
What happens to the guard cells and the stomata when the plant has a plentiful supply of water?
The guard cells become turgid making the stomata open.
243
Name the three main ways in which pathogens can be spread.
Water, air and direct contact.
244
What are pathogens?
Disease causing microorganisms.
245
How do bacteria make you ill?
They produce toxins which damage cells and tissue, this damage makes you ill.
246
How do viruses make you ill?
Viruses reproduce inside cells using the cell's machinery. The cell eventually bursts releasing new viruses. The cell damage makes you ill.
247
Name the four different pathogens.
Bacteria, Viruses, Protists and Fungi.
248
How can pathogens be spread by water?
By drinking or bathing in contaminated water.
249
How can pathogens be spread by air?
Pathogens can be carried in the are in droplets produced when people cough or sneeze.
250
State the four ways in which the spread of diseases can be reduced or prevented.
1) Being hygienic
2) Destroying vectors
3) Isolating infected individuals
4) Vaccination
251
How is the measles virus spread?
Inhalation of droplets from sneezes and coughs.
252
Why are children vaccinated against the measles virus?
Measles is a serious illness that can be fatal if complications arise.
253
What are the initial symptoms of HIV infection?
HIV initially causes a flu-like illness.
254
How is HIV spread?
By sexual contact or by exchanging bodily fluids such as blood.
255
What type of drugs are used to control HIV?
Antiretroviral drugs.
256
What do antiretroviral drugs do?
Stop the virus from replicating inside the body.
257
How does HIV lead to AIDS?
When the body's immune system becomes so badly damaged it can no longer deal with other infections or cancers.
258
What body cells does the HIV attack?
The cells of the immune system.
259
What does TMV stand for?
Tobacco mosaic virus.
260
What does TMV do to plants?
It causes mosaic like patterns on the leaves of plants causing discouloration. This means plants can't carry out photosynthesis as well, so the virus affects growth.
261
What type of pathogen is salmonella caused by?
Bacteria.
262
What symptoms might people infected with salmonella exhibit?
Fever, stomach cramps, vomiting and diarrhoea.
263
How is the spread of Salmonella controlled in the UK?
In the UK, poultry are vaccinated against Salmonella to control the spread.
264
How does a person become infected with salmonella?
By ingesting contaminated food, or food prepared in unhygienic conditions.
265
How is the bacterial disease Gonorrhoea spread?
Gonorrhoea is spread by sexual contact.
266
How can the spread of the bacterial disease Gonorrhoea be controlled?
Treatment with antibiotics or use of a barrier method of contraception e.g. condoms.
267
What are the symptoms of Gonorrhoea?
Thick yellow or green discharge from the vagina or penis and pain on urination.
268
What issues are there with the treatment for Gonorrhoea?
Was easily treated with the antibiotic penicillin until many resistant strains appeared.
269
How does rose black spot affect the leaves of a plant?
Plant develops purple or black spots on the leaves.
270
Why does rose black spot affect the growth of a plant?
The purple or black spots on leaves causes them to turn yellow and drop off, this means less photosynthesis so the plant doesn't grow as well.
271
How is rose black spot spread in the environment?
By wind or water.
272
How can gardeners treat plants infected with rose black spot?
Using fungicides and/or removing and destroying the affected leaves.
273
What type of pathogen causes malaria?
Protist.
274
How is malaria spread?
Mosquitos are vectors, they spread the disease by feeding on animals.
275
What symptoms does malaria cause?
Repeating episodes of fever. They can be fatal.
276
How is the spread of malaria controlled?
1) Destroying the mosquito vector by using insecticides
2) Stopping the mosquito vector from breeding
3) Using mosquito nets
277
What are the four first line non-specific defence systems of the human body against pathogens?
Skin, nose, trachea and bronchi, stomach.
278
What is the role of the immune system?
If a pathogen enters the body the immune system tries to destroy the pathogen.
279
Name three ways in which white blood cells help to defend against pathogens.
Phagocytosis, antibody production, antitoxin production. (Make sure you know how each of these work)
280
What happens during phagocytosis?
White blood cells engulf and digest invading pathogens.
281
What type of substances does the skin secrete that kill pathogens?
Antimicrobial substances.
282
Describe the role of the hairs and mucus in your nose in defending against pathogens.
They trap particles that could contain pathogens.
283
Describe the role of the stomach in defending against pathogens.
Produces hydrochloric acid which kills pathogens.
284
What do antitoxins do?
The neutralise the effects of toxins produced by bacteria.
285
What is the name of the unique molecules found on surface of pathogens?
Antigens.
286
What does a vaccination contain?
A small quantity of dead or inactive forms of a pathogen.
287
How does the contents of a vaccine prevent future infection?
It stimulates the white blood cells to produce specific antibodies. If the same pathogen re-enters the body the white blood cells respond quickly to produce more of the correct antibodies quickly, preventing infection.
288
State two advantages of vaccination.
1) Help control lots of communicable diseases and in some cases has eradicated some diseases.
2) Provide herd immunity - control outbreaks of a disease called epidemics
289
State two disadvantages of vaccination.
1) They don't always work.
| 2) Sometimes people have a bad reaction to the vaccine e.g. swelling
290
Which pathogens do antibiotics work against?
Bacteria.
291
Why aren't antibiotics used against viruses?
Viruses reproduce inside of cells. It is difficult to produce drugs that kill viruses without also damaging the body's tissue.
292
How do antibiotics work?
They kill the infective bacteria inside the body.
293
How are painkillers different to antibiotics?
Antibiotics kill bacteria whereas painkillers only relieve symptoms and do not kill pathogens.
294
Can a single antibiotic be used against all bacteria?
No, specific bacteria should be treated by specific antibiotics.
295
Why are antibiotic resistant strains a concern to medical professionals?
These bacteria often cause serious infection and can't be treated by antibiotics.
296
State two ways in which the rate of development of resistant strains of bacteria can be slowed down.
1) Doctors should avoid over-prescribing antibiotics.
| 2) Patients should finish the whole course of antibiotics they are given.
297
Name the drug developed from a chemical found in the willow tree.
Aspirin.
298
What is the drug aspirin used for?
Used as a painkiller and to lower fever.
299
What is digitalis used to treat?
Heart conditions.
300
The drug digitalis was developed from a chemical found in which plant?
Foxgloves.
301
Which scientist discovered the antibiotic penicillin?
Alexander Fleming.
302
What happens during preclinical testing?
The drug is tested in a laboratory on cells, tissues and live animals.
303
Which three important things are determined about the drug during drug testing?
The drug's toxicity, efficacy and optimum dose.
304
What is involved in the first stage of a clinical trial?
Clinical trials use small numbers of healthy volunteers and patients. Very low doses of the drug are given at the start of the clinical trial.
305
If a drug is found to be safe in the first stage of testing, what happens next?
If the drug is found to be safe, further clinical trials on larger groups of healthy volunteers and patients are carried out to find the optimum dose for the drug.
306
What is a double blind trial?
In double blind trials, some patients are given a placebo and the remaining patients the drug being tested. Neither the doctor nor patient know who has been given the drug or placebo. Prevents bias.
307
Why is it essential for drug trial results to be peer reviewed before they are published?
To help prevent false claims.
308
State the word equation for photosynthesis.
Carbon dioxide + water -> glucose + oxygen (light above the arrow)
309
State the balanced chemical symbol equation for photosynthesis.
6CO2 + 6H2O -> C6H12O6 + 6O2
310
Is photosynthesis an endothermic or exothermic reaction and why?
Endothermic because light energy is absorbed from the surroundings.
311
What is the main of the pigment that absorbs light in plants?
Chlorophyll.
312
In which subcellular structure does photosynthesis occur?
Chloroplasts.
313
Why is light written on top of the arrow when writing the photosynthesis equation?
Light is not a chemical so is not written as a reactant.
314
Name the three factors which affect the rate of photosynthesis.
Temperature, light intensity, carbon dioxide concentration
315
What is the inverse square law that describes how distance is linked to light intensity?
Light intensity decreases in proportion to the square of the distance. So if distance is halved light intensity increases four fold.
316
Why can’t a commercial grower of plants just increase all three limiting factors of PHS to maximum levels to obtain optimum growth?
Light, temperature and CO2 all cost money to supply – a balance between expenditure and income must be struck for a profit to be made.
317
When would we expect a higher rate of photosynthesis, at night or during the day?
During the day.
318
What is a limiting factor for photosynthesis?
A factor that stops the rate of photosynthesis from increasing any further?
319
On a graph showing light intensity against the rate of photosynthesis, what could be the limiting factors for the flat section of the graph?
Carbon dioxide concentration or temperature.
320
On a graph showing carbon dioxide concentration against the rate of photosynthesis, what could be the limiting factors for the flat section of the graph?
Temperature of light intensity.
321
Farmers use greenhouses to create the ideal conditions for plants to grow. How do they achieve this?
1) Use artificial light during the night
2) Burn paraffin heaters
3) Add fertiliser to soil
322
Describe why farmers might use paraffin heaters in a greenhouse?
1) Used to heat the greenhouse
| 2) Produces carbon dioxide - increase the level of carbon dioxide in the greenhouse
323
Use the inverse law to calculate the light intensity when a lamp is 10cm away from a plant.
1/d2 formula, 1/102 = 0.01 a.u.
324
State the 5 main ways plants use glucose.
1) For respiration
2) Making cellulose
3) Making amino acids
4) Storing as oils or fats
5) Storing as starch
325
How do plants make amino acids?
Plants combine glucose with nitrate ions.
326
Why is cellulose important for plants?
It is used to strengthen cell walls.
327
Why do plants store most of the excess glucose made as starch?
Starch is insoluble unlike glucose so water it is not drawn into the cells.
328
Is respiration an endothermic or exothermic reaction?
Exothermic.
329
State the balanced chemical equation for aerobic respiration.
C6H12O6 + 6O2 -> 6CO2 + 6H2O
330
Name the two types of respiration.
Aerobic respiration and anaerobic respiration.
331
State the difference between aerobic and anaerobic respiration.
Aerobic respiration uses oxygen, anaerobic respiration takes place without oxygen.
332
Which releases more energy, aerobic or anaerobic respiration?
Aerobic respiration
333
Where in a cell does aerobic respiration take place?
In the mitochondria.
334
Where in the cell does anaerobic respiration take place?
In the cytoplasm.
335
State the three main things organisms need energy for.
1) Chemical reactions to build and break down molecules
2) For movement
3) Keeping warm
336
State the word equation for aerobic respiration
glucose + oxygen -> carbon dioxide + water
337
What is C6H12O6
Glucose
338
State the word equation for anaerobic respiration in muscles.
glucose -> lactic acid
339
State the word equation for anaerobic respiration in plants and yeast.
glucose -> carbon dioxide + ethanol
340
What is anaerobic respiration in yeast called?
Fermentation
341
Why is fermentation by yeast important to make bread?
Fermentation refers to anaerobic respiration in yeast.
| This produces carbon dioxide that makes the bread rise.
342
Why is fermentation by yeast important for the drinks industry?
Fermentation refers to anaerobic respiration in yeast.
| This produces ethanol which is an alcohol.
343
State the three main changes in the body during exercise to the increased demand for energy.
1) Heart rate increases
2) Breathing rate increases
3) Breathing volume increases
344
Changes in your body during exercise mean more oxygen is supplied to the muscle, why?
Increase energy demand during exercise.
Aerobic respiration releases energy and requires oxygen.
More oxygen for the increased rate of respiration.
345
If an insufficient amount of oxygen is supplied to the muscle cells, what type of respiration occurs and why?
Anaerobic respiration, because this occurs in the absence of oxygen.
346
Anaerobic respiration causes the build up of which chemical in the muscles?
Lactic acid.
347
Describe the effect that long periods of vigorous exercise have on muscles.
Muscles become fatigued - tired.
| Muscles stop contracting efficiently.
348
Which process is more efficient at transferring energy from glucose in the muscles, aerobic or anaerobic respiration?
Aerobic respiration.
349
A person runs in a race, how would you expect his heart rate to change during the race?
Expect it to increase.
350
What kind of debt is created when muscles respire anaerobically?
An oxygen debt.
351
Define oxygen debt.
The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells.
352
Some of the lactic acid built up during anaerobic respiration is transported by the blood to the liver, why?
The liver converts the lactic acid back into glucose.
353
Define metabolism.
Metabolism is the sum of all the reactions in a cell
354
Lots of glucose molecules can be joined together to be stored animals. What is it stored as?
Glycogen.
355
Lots of glucose molecules can be joined together to be stored plants. What is it stored as?
Starch.
356
Glucose can be converted into a substance found in to cell wall of plants, what is this substance called?
Cellulose.
357
What is a lipid molecule made from?
One molecule of glycerol and three fatty acids.
358
How can glucose be made into proteins?
Glucose can be combined with nitrate ions to make amino acids, which are then made into proteins.
359
In which process is glucose broken down to release energy?
Respiration.
360
What is excess protein broken down into, and how is this removed from the body?
Excess protein is broken down to produce urea, which is then excreted in the urine.
