Biology Paper 1: Topics 1-5 Flashcards
1
Q
What are eukaryotic cells?
A
Complex cells. All plant and animal cells
2
Q
What are prokaryotic cells?
A
Smaller, simpler. Bacteria. Prokaryotes are single celled organisms
3
Q
What’s the nucleus?
A
Contains genetic material arranged in chromosomes, controls activities of the cell
4
Q
What’s a cytoplasm
A
Contains enzymes which Control chemical reactions that take place here
5
Q
What’s a cell membrane?
A
Holds cell together, controls what goes in and out
6
Q
What’s mitochondria
A
Where reactions for respiration (transfer energy cells need to work) occur
7
Q
What are ribosomes?
A
Involved in translation of genetic material in synthesis of proteins
8
Q
What’s a rigid cell wall
A
Made of cellulose, supports and strengthens cell
9
Q
What’s a large vacuole
A
Contains cell sap (weak solution of sugar and salts) and maintains internal pressure of cell
10
Q
What are chloroplasts
A
Where photosynthesis occurs. Contain green chlorophyll
11
Q
What’s chromosomal dna
A
Controls activities and replication, floats free in cytoplasm.
12
Q
What’s flagellum
A
Rotates to move bacterium away from harmful and towards good substances
13
Q
What’s plasmid dna
A
Small loops of extra dna, can be passed between bacteria, contain genes
14
Q
What’s a specialised cell
A
Cell with a structure adapted to its function
15
Q
What’s resolution
A
How well microscope distinguishes between two points that are close together
16
Q
What are the two types of microscope
A
Light microscope - pass light through specimen
Electron microscope - pass electrons though specimen, cant be used on living cells
17
Q
What is magnification
A
How many times bigger the image is
18
Q
What are the two equations for magnification
A
Total magnification = eyepiece lens magnification x objective lens magnification
OR
Magnification = image size / real size
19
Q
Put the four measurements smaller than cm in size order, and how do you convert between them?
A
Millimeter, mm
Micrometer, um
Nanometer, nm
Picometer, pm
Milli to micro = x1000
20
Q
What an enzyme? What’s their job?
A
A biological catalyst. Speed up useful chemical reactions in the body without being changed. Enzymes have a high specificity for their substrate because substrate must fit the active site (lock and key mechanism)
Enzymes break big molecules (proteins, lipids, carbohydrates) into smaller components, so they can be used for growth and life processes. Enzymes are also used to synthesise carbohydrates, proteins and lipids from their smaller components
Enzymes break down starch (a carbohydrate) in plants into smaller molecules that can be respired to transfer energy to be used by cells
21
Q
What’s substrate
A
Molecule changed in the reaction
22
Q
What’s an active site
A
Where enzyme joins onto substrate
23
Q
How do temperature, ph and substrate concentration affect rate of enzyme controlled reaction?
A
Temperature = higher temp increases rate until enzyme denatures. Optimum temperature is different for all enzymes
pH = too high or too low pH denatures the enzyme. Optimum pH often 7
Substrate concentration = higher substrate concentration > faster reaction, because more likely an enzyme will encounter a substrate molecule. When all active sites full, further increase in substrate concentration makes no difference
24
Q
What’s denaturing of enzyme?
A
Some bonds holding enzyme together break, causing shape of enzyme’s active site to change. Substrate will no longer fit.
25
What’s an experiment to investigate effect of pH on enzyme activity?
Use continuous sampling to time how long it takes amylase to break down all starch solution, when mixed with buffer solutions of various pHs. Detect starch using iodine solution, changes from orange to black if starch present
26
What’s the two equations for rate of reaction?
If experiment is measuring how much something changes over time:
Rate of reaction = change / time
OR
Rate of reaction = 1000 / time
27
What do digestive enzymes do?
Break down food into smaller, soluble molecules that can then easily pass through walls of digestive system, so can be absorbed into bloodstream, then pass into cells for use in the body
28
What are the big molecules carbohydrates, proteins and lipids broken down into and how?
Carbohydrates > simple sugars, by carbohydrase enzymes.
Eg: starch (amylase enzyme) > maltose + other sugars
Proteins > amino acids, by protease enzymes
Lipids > glycerol + fatty acids, by lipase enzymes
29
What’s glycogen and hows it made?
Chains of glucose molecules broken down into glycogen using glycogen synthase enzyme.
Glycogen is a molecule used to store energy in animals
30
What’s diffusion?
The net (overall) movement of particles from an area of higher concentration to an area of lower concentration.
It moves down the concentration gradient therefore is passive movement, happens in liquids and gases. Only small molecules can dissolve through cell membranes
31
What’s osmosis?
The net movement of water molecules across a partially permeable membrane (membrane with small holes in), from a region of higher water concentration to a region of lower water concentration (water can be replaced by ‘solute’)
Solute solution will become more dilute with osmosis
32
What’s active transport
Movement of particles across a membrane against a concentration gradient (lower to higher) using energy transferred during respiration
33
What’s an experiment for investigating osmosis
Put potato cylinder groups of 3 in sucrose solutions of different concentrations, then calculate percentage change in mass for each cylinder group before and after going into sucrose. Negative result means cylinders lost mass
Percentage change in mass = ((final mass - initial mass) / initial mass) x 100
34
On a graph plotted for the ‘investigating osmosis’ experiment, what do __ mean:
- points above x axis
- where curve crosses x axis
- points below x axis
Above; water concentration of sucrose solution is higher than in cylinders. Cylinders gained mass, water drawn in by osmosis
Curve crosses x axis; fluid inside cylinders and sucrose solution are isotonic = have same wate concentration
Points below x axis; water concentration of sucrose solutions lower than in the cylinders. Cylinders lose water, so mass decreases
35
What are chromosomes
Coiled up lengths of DNA molecules. A diploid cell has two copies of each chromosome
36
Whats the cell cycle
Body cells in multicellular organisms undergo the cell cycle
It’s mitosis and cytokinesis, and then interphase
Mitosis: stage of cell cycle when the cell divides. Organisms use mitosis to grow or replace damaged cells, or to asexually reproduce. Mitosis produces two genetically identical diploid cells.
Interphase: DNA is spread out in long strings, cell growing to increase number of sub cellular structures. DNA duplicates and forms x shaped chromosomes (with identical left and right arms)
37
Describe what happens in each cell of the cell cycle
Interphase: DNA duplicates forming x-shaped chromosomes
Mitosis and cytokinesis:
Mitosis:
1 Prophase: chromosomes condense, lie free in cytoplasm as membrane around nucleus breaks down
2 Metaphase: chromosomes form a line at centre of cell (equator)
3 Anaphase: Cell fibres (formed by centrioles) pull chromosomes apart at the centromeres (middle bits of chromosomes), each arm (chromatid) of each chromosome go to opposite ends of cell
4 Telophase: Membranes form around each of the sets of chromosomes (these become nuclei of new cells)
Cytokinesis: Before Telophase ends cytoplasm and cell membrane divide to form two separate ends
38
Whats equation to calculate number of cells after multiple divisions of a cell by mitosis
Number of cells = 2^n, n being the number of divisions by mitosis
39
What’s ‘cell growth’ defined as
An increase in size or mass. All growth in animals is done by cell division, plants grow by cell elongation, with cell division happening at tips of roots and shoots.
40
What’s cell differentiation?
Cell changes to become specialised, allowing multicellular organisms to work more efficiently.
41
On a growth percentile chart, what does the 50th percentile for eg weight tell you?
Shows weight that 50% of babies will have reached at a certain age
42
What are stem cells? What are the different types?
Undifferentiated cells. Can divided by mitosis to become new cells that then dissociate.
Embryonic stem cells = found in embryos, have potential to divide and become any type of cell. Essential for growth and development of organisms
Adult stem cells = only found in certain places, eg bone marrow. Can only produce certain cell types, use to replace damaged cells
In plants, stem cells found in meristem tissue, which is found in areas of plant that are growing. Can divide into any cell type.
43
What’s the nervous system made of?
Neurones (nerve cells)
44
What are sensory receptors?
Group of cells that detect stimulus, a change in environment. Different receptors detect different stimulus. When stimulus detected by receptors, it’s converted to a nervous electrical impulse, sent along sensory neurones to CNS
45
What’s the CNS made of
CNS = central nervous system, made of brain and spinal cord. It coordinates response, as impulses travel through CNS along relay neurones. CNS sends information to an effector (muscle or gland) along motor neurone. Effector responds accordingly
46
Whats reaction time?
Time taken to respond to stimulus
47
Outline the overall path of the CNS
Stimulus > receptor > sensory neurone > CNS > motor neurone > effector > response
48
What are neurones
All neurones have cell body, nucleus and sub cellular structures. Cell body has extensions connected to other neurones.
Neurones are long to speed up the impulse travel. One neurone faster than many small connected neurones
49
What do dendrites and dendrons do?
Carry nerve impulses towards cell body
50
What are axons?
They Carry impulses away from cell body
Some axons surrounded by myelin sheath, which acts as an electrical insulator, speeding up the electrical impulse
51
What’s a sensory neurone?
1 long dendrologisch carries nerve impulses from receptor cells to cell body (located in middle of neurones), 1 short axon carries impulses from cell body to CNS
52
What’s a motor neurone?
Many short dendrites carry nerve impulses from CNS to cell body, 1 long axon carries impulses from cell body to effector cells
53
What’s a relay neurone
Many short dendrites carry nerve impulses from sensory neurones to the cell body. An axon carries nerve impulses from cell body to motor neurones
54
What’s a synapse
A connection between two neurones.
55
How are nerve signals transferred
By neurotransmitter chemicals. They diffuse across the gap, then set off new electrical signal in the next Neurone
56
What’s a reflex? What’s a reflex arc?
Reflex is an automatic response to stimuli
| A reflex arc is a passage of information in a reflex, from receptor to effector
57
Describe the five steps of a ‘reflex arc’
1 stimulus detected, impulses sent along sensory neurone to a relay neurone in the CNS
2 impulses trigger release of neurotransmitters when they reach a synapse between sensory neurone and relay neurone. Neurotransmitters cause impulses to be sent along relay neurone
3 when impulse reaches synapse between relay neurone and motor neurone, neurotransmitters are released and cause impulses to be sent along the motor neurone
4 impulses travel along motor neurone to effector
5 effector reacts accordingly
58
Describe the path of the eye protection reflex
Light receptors in eye detect bright light, send message along sensory neurone to brain
Message travels along relay neurone to a motor neurone, which tells circular muscles in iris to contract
59
What’s sexual reproduction.
When genetic information from two organisms is combined to produce offspring genetically different to either parent. During sexual reproduction, father and mother produce gametes, which are haploid reproductive cells
60
What’s a haploid cell and whats a diploid cell?
```
Haploid = half number of chromosomes, 23 chromosome cell
Diploid = 46 chromosome cell
```
61
What’s a zygote
A diploid, fertilised egg. Made by gametes fusing at fertilisation. Zygote undergoes mitosis to turn into an embryo, which receives a mixture of chromosomes, meaning mixed genes, meaning mixed characteristics
62
In plants where are the gametes found?
Male gametes found in Pollen, female in ovaries at base of stigma
63
What’s purpose of meiosis.
To produce 4 gametes which are genetically varied.
It produces 4 haploid daughter cells, which are called gametes. Each gamete has a single set of chromosomes. These gametes are all genetically different
64
What is DNA?
DNA is repeating units of nucleotides, which are made of sugar, a phosphate and bases (AGCT). DNA molecule has 2 strands coiled together in a double helix, where each base links to a base on the opposite stand in the helix. These complementary base pairs are joined together by weak hydrogen bonds
DNA strands are polymers, meaning made up of many repeating units joined together. Each unit contains 1 of the 4 bases
65
What are the four bases each unit in a DNA strand contains.
Adenine, Thymine, Cytosine, Guanine
A and T are complementary base pairs
C and G are complementary base pairs
66
What are chromosomes?
Long coiled up molecules of DNA found in the nucleus of eukaryotic cells. There are 23 matched pairs of chromosomes in every human body cell
67
What’s a gene
A section of DNA which codes for a particular protein. sequence of bases in gene determine what protein is produced
68
What’s the genome?
All of an organisms DNA
69
What experiment can we do to see DNA?
Extracting DNA from fruit cells. Use detergent to break down cell membranes. Salt makes DNA stick together. Filter and add ice cold alcohol and DNA will come out of solution because it’s not soluble in cold alcohol.
70
What are alleles?
Different variations of genes. You have two alleles of every gene, one on each chromosome in a pair
71
What does homozygous and heterozygous mean?
Homozygous for a trait means organism has two alleles for a particular gene
Heterozygous means two alleles for a gene are different. Dominant alleles will overrule the recessive alleles
72
What’s a phenotype and what’s a genotype
Phenotype is what characteristics an organism displays
| Genotype is what combination of alleles you have
73
What’s monohybrid inheritance? How can you show it?
The inheritance of a single characteristic. Can use a punnet square or monohybrid cross to show monohybrid inheritance
74
What’s a family pedigree
A family tree of genetic disorders. A carrier is someone who has 1 copy of the recessive allele, so don’t develop the disorder. Family pedigree should include a key.
75
What are the two possible types of variation within a species
Genetic variation: caused by organisms having different alleles leading to difference in phenotypes
Environmental variation: caused by the environment, ie the conditions in which the organisms live
Environmental variation also known as ‘acquired characteristics’
76
What’s a mutation?
Changes to the base sequence of DNA. A mutation in a gene makes an allele. New combinations of alleles may interact to produce new phenotypes. A neutral mutation means a mutation that has no effect on the phenotype
77
What’s the human genome project?
Thousands of scientists collaborated to find every single human gene. Complete map of human genome completed in 2003. Scientists must not discover what all these genes do.
Used for prediction and prevention of diseases, testing and treatment for inherited disorders. Helps develop new and better medicines.
78
What are selection pressures
Factors that affect the organisms chance of surviving and reproducing
79
What’s natural selection?
An organisms characteristics are advantageous to its survival, therefore its more likely to survive and pass on these alleles to offspring. Over time, many in the species will end up with this characteristic. This is evolution
80
What’s a fossil defined as
Any trace of an animal or plant that lived a considerable amount of time ago. Arranging fossils in chronological order shows gradual changes in organisms, which shows how the species change and develop over time.
81
What are the three example pieces of hominid fossil evidence for human evolution over millions of years
Ardi - ardipithecus ramidus species - 4.4 million years old
Mixed ape and human features. Walked upright without hands for help. Climbed lots.
Lucy - Australopithecus Afarensis - 3.2 million years old
Mix human and ape features, more human. Didn’t climb much. Walked upright
Turkana Boy - homoerectus - 1.6 Million years old
Mix human + ape features, even more human. Walked upright. Humanoid figure.
82
How do you calculate brain size of a fossil
Calculate its cranial capacity, the space taken up by brain in the skull
83
Three way scientists work out age of hominid fossils or ancient tools
Look at structural features + what’s found around it
Use carbon - 14 dating, as stone tools usually found with a carbon containing material
Use stratigraphy, the study of rock layers
84
What are the parts of the five kingdom classification system
```
0.5 = Domain (Archaea, Bacteria or Eukarya)
1 = kingdom; animals, plants, fungi, prokaryotes (archaea or bacteria), protists
2 = phylum
3 = class
4 = order
5 = family
6 = genus
7 = species
```
85
What are protists?
Eukaryotic single celled organisms
86
How are all organisms classified?
Classified by characteristics and cell structure, the more similar the sequence of DNA bases in different organism’s genes, the more closely related they are.
All organism’s divided into 3 domains:
1 Archaea; organisms that look similar to bacteria but have different genetic sequences to bacteria
2 Bacteria; contains true bacteria
3 Eukarya; a broad range of organisms including fungi, plants, animals and protists
87
What’s selective breeding
When humans artificially select the plants or animals that are going to breed so the genes for particular characteristics remain in the population. This is continued over several generations so desired trait gets stronger and stronger.
Important in agriculture, medical research. However reduces gene pool through inbreeding
88
What’s genetic engineering? Describe the process
Genetic engineering = modifying an organisms genome to introduce desirable characteristics
1 DNA want to insert cut out using restriction enzyme. Vector DNA cut open using same restriction enzyme
2 Vector DNA + inserting DNA both have sticky ends. Mix together with ligase enzyme.
3 Ligases join pieces of DNA together to make recombinant DNA
4 Recombinant DNA inserted into other cells, which can now use the gene you inserted to make the desired protein
Used in agricultures and medicine
89
What are restriction enzymes and what are ligase enzymes?
Restriction enzymes recognise specific sequences of DNA and cut the DNA of these points, leaving DNA with sticky ends at cutting points
Ligase enzymes are used to join two pieces of DNA together at sticky ends
90
What’s recombinant DNA?
Two different bits of DNA stuck together
91
What’s a vector? What are plasmids?
Vector = something used to transfer DNA into a cell
Plasmids = small, circular molecules of DNA, transferred between bacteria
92
How do viruses work?
They insert DNA into organisms they want to infect. A virus is a protein coat around a strand of genetic material, they infect specific host cells in order to reproduce
93
What is health defined as? What’s an infirmity?
Health means physical, mental and social wellbeing.
| Infirmity is a weakness of frailness, usually caused by old age
94
What’s a disease? What are the types of diseases?
A disease is a condition where part of an organism doesn’t function properly
Communicable diseases; can be spread between individuals
Non communicable diseases; can’t be transmitted between individuals
Being infected by one disease can make you more susceptible to others
95
What’s susceptible mean?
Increased chance of getting a specific disease
96
What are pathogens?
Organisms such as viruses, bacteria, fungi or protists that cause communicable diseases
97
Describe Cholera, Tuberculosis, Malaria and Chalara Ash Dieback
Cholera; caused buy bacteria in contaminated water sources. Causes diarrhoea.
Tuberculosis; caused by bacterium in air, causes coughing + lung damage
Malaria; cause by protists, mosquitoes are animal vectors. Damage red blood cells.
Chalara Ash Dieback; fungus which infects Ash Trees, carried in air. Causes bark lesions.
98
What’s an STI? Describe two examples of STIs.
Sexually transmitted infections, spread though sexual contact
HIV or Human Immunodeficiency Virus; infects and kills white blood cells, eventually causing AIDs (hosts immune system fails) spread via bodily fluids. Medication can reduce risk
Chlamydia is a bacterial infection. Bacterium which can only reproduce inside host cells. Can result in infertility. Spread by genital contact.
99
What are the two types of defence against pathogen entry?
Physical barriers (skin, hair, mucus) and chemical barriers (hydrochloride acid in stomach, chemical lysozyme produced in eyes)
100
Describe How does immune system work
It destroys pathogens in the body. White blood cells travel through body in blood stream:
B-lymphocytes; type of white blood cell. Involved in specific immune response.
B-lymphocytes detect antigen on pathogen and starts producing proteins called antibodies specific to that pathogen, which bind to the pathogen. Antibodies then produced rapidly, flowing around body to find all similar pathogens
101
What’s specific immune response
The immune response to a specific pathogen
102
What’s are antigens?
Unique molecules on surface of every pathogen
103
How does immunisation work
Memory lymphocytes produced in response to a foreign antigen. They remain in the body and ‘remember’ a specific antigen, so a secondary immune response will be faster and stronger
Immunisation involves injecting dead or inactive antigenic (carries antigens) pathogens. Body makes antibodies, antigens trigger memory lymphocytes to be made.
104
What do antibiotics do?
They treat bacterial infections by inhibiting processes in bacterial cells and not the host organism
105
Describe the stages of developing a drug
- Preclinical testing:
1 drug tested on human cells + tissue (doesn’t work if drug affects whole or multiple body systems)
2 Drug tested on live animals
- Clinical testing
1) Tested on human volunteers in a clinical trial
- tested on healthy volunteers for side effects
- tested on people suffering from illness, optimum dosage (most effective with fewest side effects) found
- Blind clinical trial (allows for placebo effect)
- approval by a medical agency
106
What are risk factors?
Factors linked to increase of likelihood a person will develop a disease. Some risks factors are unavoidable, eg age/gender. Some risk factors caused by lifestyle choices, eg smoking; nicotine increases bp, damaging artery walls,restricting blood flow and increased risk of blood clots, so increased likelihood of developing cardiovascular disease
Non communicable diseases caused by multiple risk factors interacting
107
What lifestyle choices lead to increased risk factors of; scurvy, obesity, liver damage, type 2 diabetes
Too many/few nutrients > malnutrition > disease eg scurvy
Not enough exercise + diet high in fat and sugar > take in more energy than used >obesity
Too much alcohol > liver disease + permanent liver damage
Obesity > type 2 diabetes + cardiovascular disease
108
What’s BMI and hows it measured?
Body mass index, helps decide if someone is underweight, normal, overweight or obese
BMI = weight (kg) / height (m)^2
BMI not always accurate to measure if someone’s obese, because muscle weighs more than fat
109
Equation for waist to hip ratio
Waist to hip ratio = waist circumference / hip circumference
Abdominal obesity = high waist to hip ratio. Greater risk of developing obesity related health problems
110
What’s cardiovascular disease?
Any disease associated with heart + blood vessels
111
What are arteries?
Blood vessels that carry blood away from the heart
112
What’s cholesterol?
A fatty substance, used to make things like cell membranes. Too much of it in blood leads to fatty deposits in arteries in places the arteries have been damaged, restricting blood flow and also triggering blood clots to form, blocking blood flow completely
113
What’s a heart attack? What’s a stroke?
Heart attack = artery supplying heart muscle clots, depriving heart of oxygen
Stroke = blood clots in brain, deprives brain of oxygen
114
What are responses you should take to heart attack or stroke?
Lifestyle changes; diet low in saturated fat, exercise regularly,
Drugs:
Statins - reduce cholesterol, slow rate fatty deposits form, cause aching muscles and possible permanent liver damage
Anticoagulants- makes blood clots less likely to form, can cause excessive bleeding if person injured
Antihypertensives- reduce blood pressure, prevents damage to blood vessels, reduce risk of fatty deposits forming. Can cause headaches and fainting.
Surgical procedures:
Coronary bypass surgery - piece of healthy vessel used to bypass blocked section of blood vessel
Stents - tubes inserted into artery, keep them open. Causes scar tissue over time that narrows artery and blood can clot on the stent
Heart replaced by donor heart
115
What’s an independent variable?
Dependant variable?
Control variable?
Independent - the thing we change in experiment
Dependant - the thing we measure
Control - remains the same
