Edexcel Biology- Paper 1 (all) Flashcards
(169 cards)
1
Q
What are light microscopes?
A
Light microscopes are cheap to make and allow you to see the outlines of cells.
2
Q
What do electron microscopes allow you to visualize?
A
Electron microscopes allow you to visualize finer details including organelles due to their greater resolving power and higher resolution.
3
Q
What is the prefix for millimetre?
A
The prefix for millimetre is mm, which equals 1x10^-3 m.
4
Q
What is the prefix for micrometre?
A
The prefix for micrometre is um, which equals 1x10^-6 m.
5
Q
What is the prefix for nanometer?
A
The prefix for nanometer is nm, which equals 1x10^-9 m.
6
Q
What is the prefix for picometer?
A
The prefix for picometer is pm, which equals 1x10^-12 m.
7
Q
How is magnification calculated?
A
Magnification = image size / object (cell) size.
8
Q
What is the typical length of cells?
A
Cells are usually a few micrometers (um) long.
9
Q
How do you convert micrometers to millimeters?
A
To convert micrometers to millimeters, divide by 1000.
10
Q
What is the function of the cell membrane?
A
It is semi-permeable and controls what enters and leaves the cell.
11
Q
What does the nucleus contain?
A
DNA.
12
Q
What is the primary function of mitochondria?
A
Respiration.
13
Q
What is the role of cytoplasm?
A
It is the gel-like substance within the cell.
14
Q
What is the function of ribosomes?
A
Protein synthesis.
15
Q
What is the role of chloroplasts?
A
They contain chlorophyll and are involved in photosynthesis.
16
Q
What is a characteristic of prokaryotic cells?
A
They have DNA in the cytoplasm.
17
Q
What is the function of a flagellum?
A
It acts as a tail for moving.
18
Q
What is the composition of the cell wall in prokaryotic cells?
A
It is made of cellulose.
19
Q
What is the purpose of a permanent vacuole?
A
It stores sap.
20
Q
What are enzymes?
A
Enzymes are special proteins that act as biological catalysts.
21
Q
What do carbohydrases do?
A
Carbohydrases break down carbohydrates into simple sugars.
22
Q
What is the ‘lock and key’ principle?
A
Enzymes are specific and only break down substrates that fit their active site.
23
Q
What is an enzyme-substrate complex?
A
An enzyme-substrate complex is formed when an enzyme binds to its substrate.
24
Q
How does temperature affect enzyme activity?
A
Activity increases with temperature until the enzyme denatures.
25
What happens to enzymes at extreme pH levels?
Enzymes can denature at too high or low pH.
26
What are lipases responsible for?
Lipases break down lipids into glycerol and fatty acids.
27
What is the optimum condition for enzyme activity?
Optimum is the condition for maximum rate/activity.
28
What is the practical method to test amylase activity?
Mix amylase with starch, remove drops every 10 seconds, and add to iodine.
29
How do you determine the optimum pH or temperature?
The optimum pH/temp is between the two lowest times recorded.
30
What happens to iodine when starch is present?
Iodine turns from orange to black.
31
What is the color change of Biuret's reagent in the presence of protein?
Biuret's reagent changes from blue to purple.
32
What happens to Benedict's solution in the presence of sugars?
Benedict's solution changes from blue to green/yellow to orange to brick red.
## Footnote
This is a semi-quantitative test.
33
What indicates the presence of lipids (fats)?
Cold ethanol turns cloudy.
## Footnote
An alternative test is Sudan III, which causes two layers to form, with the top layer being brick red.
34
What is diffusion?
Diffusion is the movement of particles from an area of high concentration to an area of low concentration (down the concentration gradient). This process is passive as it requires no energy.
35
What factors can increase the rate of diffusion?
The rate of diffusion can be increased by increasing the difference in concentrations, surface area, or temperature.
36
What is osmosis?
Osmosis is the diffusion of water across a semi-permeable membrane to balance the concentrations of solution inside and outside a cell.
37
What drives water movement in osmosis?
Water moves in if the concentration is higher outside, as larger molecules cannot fit through the holes of the membrane.
38
What is active transport?
Active transport is the movement of particles through a membrane via carrier proteins. This process requires energy and can move particles against the concentration gradient.
39
What is the procedure for the osmosis practical?
Weigh and place identical cylinders from the same vegetable in sugar solutions of varying concentrations. After a set time, remove excess water and reweigh.
40
How do you calculate the percentage change in mass in the osmosis practical?
Calculate % change in mass = (final mass - initial mass) x 100 / initial mass.
41
What do you plot in the osmosis practical?
Plot % change in mass against concentration. Using the line of best fit, the concentration at 0% change in mass is the same as inside the vegetable.
42
What is the chromosome configuration in human cells?
All human cells have 23 pairs of chromosomes (diploid), except gametes (eggs/sperm) that have just 23 (haploid).
43
What process produces new diploid cells?
New diploid cells are made by mitosis, for growth and repair.
44
What occurs during interphase in mitosis?
Genetic material is duplicated.
45
What happens during prophase?
The nucleus membrane dissolves.
46
What occurs during metaphase?
The two sets of chromosomes line up in the middle.
47
What happens during anaphase?
The chromosomes are pulled to opposite sides of the cell.
48
What occurs during telophase?
Mitochondria, ribosomes, and other organelles are duplicated, and new membranes are formed around the two sets of chromosomes to make two nuclei.
49
What is the final step of mitosis?
The cell divides (cytokinesis), producing two genetically identical diploid cells.
50
What is cancer in relation to cell division?
Cancer is characterized by damaged cells that divide uncontrollably.
51
What can stem cells do?
Stem cells can differentiate (or 'specialise') to perform specific functions.
52
Where are stem cells found?
Stem cells are found in animal embryos and plant meristems.
53
Where are some stem cells still made in the body?
Some stem cells are still made in your bone marrow.
54
What can bone marrow stem cells specialise into?
Bone marrow stem cells can only specialise into blood cells.
55
What can be made from embryo clones?
Embryo clones can be made of a person to harvest stem cells from.
56
Why are embryo clones used for harvesting stem cells?
They can be used to treat conditions without being rejected by the patient's body.
57
What are two uses of cloning?
Cloning can be used to preserve species or produce crops with desired traits.
58
What can stem cells do?
Stem cells can differentiate (or 'specialise') to perform specific functions.
59
Where are stem cells found?
Stem cells are found in animal embryos and plant meristems.
60
Where are some stem cells still made in the body?
Some stem cells are still made in your bone marrow.
61
What can bone marrow stem cells specialise into?
Bone marrow stem cells can only specialise into blood cells.
62
What can be made from embryo clones?
Embryo clones can be made of a person to harvest stem cells from.
63
Why are embryo clones used for harvesting stem cells?
They can be used to treat conditions without being rejected by the patient's body.
64
What are two uses of cloning?
Cloning can be used to preserve species or produce crops with desired traits.
65
What does CNS stand for?
Central Nervous System (brain & spinal cord)
66
What does PNS stand for?
Peripheral Nervous System (all other nerves)
67
What is a synapse?
A junction between two neurones where neurotransmitters are released.
68
What is a motor neurone?
A type of neurone that carries signals from the CNS to effectors.
69
What is a receptor?
A structure that detects stimuli.
70
What is an effector?
A structure that produces a response to a stimulus.
71
What is a sensory neurone?
A type of neurone that carries signals from receptors to the CNS.
72
What is a relay neurone?
A type of neurone that connects sensory and motor neurones within the CNS.
73
What is a reflex arc?
A neural pathway that bypasses the brain for quicker responses.
74
What role do glands play in the nervous system?
Glands are effectors that secrete chemicals.
75
What is a neurotransmitter?
A chemical that transmits signals across a synapse.
76
What is the practical method for measuring reaction times?
Drop a ruler between finger & thumb, measure distance fallen before caught, repeat, calculate mean.
77
What is the independent variable in the reaction time practical?
Stimulant (e.g. energy drink) increases neurotransmission; depressant (e.g. alcohol) decreases neurotransmission.
78
What formula could be used to calculate reaction time?
s = ¼at
79
What is meiosis?
The process by which gametes are made - genetically different from parent cells.
## Footnote
Mitosis produces identical cells.
80
How many pairs of chromosomes are in a diploid cell?
23 pairs of chromosomes.
81
What happens to similar chromosomes during meiosis?
They pair up and genes are swapped between them.
82
What is the result of the first cell division in meiosis?
It produces two diploid cells.
83
What is the final outcome of meiosis?
It produces 4 haploid cells (gametes).
84
What is a genome?
The entire genetic code in an organism.
85
What is DNA?
A double helix polymer that stores genetic code.
86
What is a gene?
A portion of DNA that codes for a protein.
## Footnote
Mapping these allows us to identify causes of disorders.
87
What is a genotype?
An organism's specific genetic code.
88
What is a phenotype?
How the genotype is expressed in physical characteristics.
89
What are monomers/nucleotides/bases made from?
A sugar/phosphate group.
90
What are the base pairs in DNA?
A+T and C+G. Every three bases code for an amino acid.
91
What is protein synthesis?
The process where the code is copied by mRNA (transcription), taken to the ribosome, which assembles amino acids into polypeptides then proteins (translation) that are then folded into shape.
92
What can mutations result in?
Wrong proteins being synthesized.
93
What determines characteristics in organisms?
Characteristics are determined by the type and quantity of proteins synthesised.
94
What are alleles?
Different versions of the same gene are called ALLELES.
95
What is a dominant allele?
DOMINANT alleles e.g. 'B' are expressed even when genotype contains a RECESSIVE allele e.g. 'b'.
96
When is a recessive allele expressed?
There must be no dominant allele in order for a recessive allele to be expressed in the phenotype.
97
What are homozygous alleles?
BB and bb are HOMOZYGOUS alleles.
98
What are heterozygous alleles?
Bb is HETEROZYGOUS.
99
What condition is caused by a dominant allele?
POLYDACTYLY is caused by a dominant allele.
100
What condition is due to a recessive allele?
CYSTIC FIBROSIS is due to a recessive one.
101
What are the sex chromosomes for females?
Females have XX chromosomes.
102
What are the sex chromosomes for males?
Males have XY chromosomes.
103
What is a Punnett Square used for?
A Punnett Square is used to predict the probability of offspring genotypes.
104
What is the chance of having a child with blue eyes if one parent is Bb?
25% chance of having I (carrier) blue eyes.
105
What is the chance of a child having cystic fibrosis if one parent is Cc?
25% chance child will have cystic fibrosis.
106
What is the chance of having a girl or boy if one parent is XX and the other is XY?
50% chance girl, 50% chance boy.
107
What causes variation in offspring?
Variation in offspring is a result of both genetic and environmental factors.
108
What is Darwin's theory of evolution?
Random mutations result in variation; some organisms are better adapted to their environment.
109
How are organisms classified as the same species?
Organisms are considered to be of the same species if they can produce fertile offspring.
110
What is 'survival of the fittest'?
It refers to the competition among organisms, where those better adapted are more likely to survive.
111
What happens to desirable characteristics over time?
Over time, desirable characteristics become more pronounced in a population.
112
What is Lamarck's theory of evolution?
Mutations/adaptations are a result of the environment affecting characteristics inherited by offspring; they are not random.
113
What is selective breeding?
Breeding organisms that have desired characteristics to produce offspring in which those characteristics are more pronounced.
114
How is antibiotic-resistant bacteria evidence for Darwinian evolution?
If not all bacteria are killed, those most resistant will reproduce, demonstrating natural selection.
115
Why is it important to complete the full course of antibiotics?
Completing the full course ensures that all bacteria are killed, preventing the survival of resistant strains.
116
Who was one of the first to believe that characteristics were inherited?
Mendel was one of the first to believe that characteristics were passed down due to inherited 'units'.
117
What is genetic modification?
The insertion of a gene into an organism's genome so it synthesises a specific protein to achieve a desired characteristic.
118
What are some examples of genetic modification?
- Insulin-producing bacteria.
- Creating GM (Genetically Modified) crops, e.g. golden rice which produces Vitamin A.
- Disease-resistant crops.
119
What is the first step in genetic modification?
Desired gene is cut from another organism's DNA using restriction enzymes, leaving it with sticky ends.
120
What is the second step in genetic modification?
Gene inserted into a vector, e.g. bacteria plasmid or virus using ligase enzyme.
121
What is the third step in genetic modification?
Vector inserts gene into cells of another organism early in development due to every cell synthesising that specific protein.
122
What is a vector in genetic modification?
A vehicle, such as a bacteria plasmid or virus, used to insert a gene into another organism.
123
What are fossils?
Fossils are the decayed remains of organisms or evidence of their existence.
124
What happens to bones in fossils?
Fossils that look like bones are actually bones that have been replaced with minerals.
125
Can fossils contain soft organic tissue?
Some fossils can still have soft organic tissue if the conditions for decay are not present.
126
What are examples of fossils besides bones?
Footprints that have hardened in mud are considered fossils, as are other traces of organisms left behind.
127
What are non-communicable diseases?
Diseases caused by factors inside the body.
128
What are examples of non-communicable diseases?
1. Diabetes: obesity & poor diet increase risk.
2. Heart Disease/CVD/CHD: diet, smoking & lack of exercise increase risk.
3. Liver Disease: alcohol increases risk.
4. Lung Disease/Cancer: smoking increases risk.
5. Cancer: caused by genetic mutations in cells.
129
What is the difference between benign and malignant tumors?
Benign tumors do not spread, while malignant tumors spread through the body.
130
What are carcinogens?
Substances that increase the risk of developing cancer.
131
What are non-communicable diseases?
Diseases caused by factors originating from inside the body.
132
What are some examples of non-communicable diseases?
Diabetes, heart disease (CVD/CHD), liver disease, lung disease (cancer), and cancer.
133
What increases the risk of diabetes?
Obesity and poor diet.
134
What factors increase the risk of heart disease?
Diet, smoking, and lack of exercise.
135
What increases the risk of liver disease?
Alcohol consumption.
136
What increases the risk of lung disease and cancer?
Smoking.
137
What causes cancer?
Genetic mutations in cells that cause them to multiply uncontrollably, forming a tumor.
138
What are carcinogens?
Substances that increase the risk of developing cancer.
139
What is the difference between benign and malignant tumors?
Benign tumors do not spread, while malignant tumors spread through the body.
140
How is BMI calculated?
BMI = mass (kg) / height (m)²
## Footnote
Normal BMI range is 18.5 - 25.
141
What is a pathogen?
A micro-organism that causes disease: BACTERIA, VIRUSES, FUNGI or PROTISTS
142
How do viruses reproduce?
Some infect and reproduce in other cells by replicating their DNA and protein coat (lytic pathway), while others (phages) reproduce by inserting DNA into cells which causes them to produce more copies (lysogenic pathway). Cell bursts (lysis) releasing them.
143
What does HIV do?
Destroys WBC, leads to AIDS. STI/STD (sexually transmitted)
144
What does Ebola cause?
Causes haemorrhaging (internal bleeding).
## Footnote
Vector: bodily fluids
145
How do bacteria affect the body?
Release toxins into your body that damage cells.
146
What does cholera cause?
Causes diarrhoea.
## Footnote
Vector: water
147
What does tuberculosis cause?
Causes lung damage.
## Footnote
Vector: air (airborne)
148
What does Helicobacter cause?
Causes stomach ulcers.
## Footnote
Oral transmission
149
What is chlamydia?
STI/STD
150
How do fungi affect cells?
Damage cells.
151
What does Chalara ash dieback cause?
Causes leaf loss & bark lesions on plants.
## Footnote
Airborne
152
What is athlete's foot?
A fungal infection.
153
What are protists?
Single-celled organisms.
154
What does malaria damage?
Damages RBC and liver.
## Footnote
Vector: mosquitoes
155
What are the primary defenses of the skin and respiratory system?
Skin acts as a barrier, while mucus in the nose and trachea traps pathogens. Acid and enzymes kill pathogens.
156
What defenses do plants have against pathogens?
Plants have cell walls, waxy cuticles, and bark as barriers; they also produce antibacterial chemicals and use poisons or thorns to deter organisms.
157
What do lymphocytes produce to combat pathogens?
Lymphocytes produce antitoxins to neutralize toxins and antibodies that bind to the antigens of pathogens.
158
What is the role of antibodies in the immune response?
Antibodies stop viruses from infecting cells and cause them to clump together.
159
What happens once the correct antibody is found?
T cells store the antibody in lymph nodes for future immunity.
160
What is the function of phagocytes?
Phagocytes ingest pathogens.
161
What is a vaccine?
A vaccine introduces a dead or inert version of a virus into the body to gain immunity without causing illness.
162
What do antibiotics kill?
Antibiotics kill bacteria, but not viruses.
163
What is a challenge in antibiotic development?
It is difficult to make them target specific bacteria without damaging our cells or other 'good' bacteria.
164
Why must a whole course of antibiotics be taken?
The whole course must be taken to kill all bacteria, or more resistant bacteria will survive and multiply.
165
What is an example of a drug derived from nature?
Aspirin (a painkiller) came from trees.
## Footnote
Another example is Penicillin, which came from a mould.
166
What are synthetic drugs known for?
Synthetic drugs cost a lot of money to develop.
167
What trials do synthetic drugs go through?
They are put through trials to assess for efficacy, toxicity, and dose.
168
What is a blind trial?
In a blind trial, the test group is given the drug, and the control group is given a placebo without being made aware.
169
What is a double blind trial?
In a double blind trial, doctors do not know which group is receiving the drug or the placebo to eliminate bias.
