Biology paper 1 Flashcards
(110 cards)
1
Q
What are the stages of Mitosis?
A
(Interphase,) Prophase, Metaphase, Anaphase, Telophase (and Cytokinesis)
2
Q
What happens in Interphase?
A
Normal cell processes, DNA replication
3
Q
What happens at prophase?
A
Cell membrane around nucleus disappears and chromosomes condense
4
Q
What happens at Metaphase?
A
Chromosomes line up in the centre of the cell
5
Q
What happens at Anaphase?
A
Spindle fibres pull chromosomes to opposite poles of the cell
6
Q
What happens at Telophase?
A
new membrane forms around the chromosomes
7
Q
What happens at Cytokinesis?
A
cell membrane pinches and cell divides into 2 cells
8
Q
What does mitosis produce?
A
2 genetically identical diploid daughter cells (46)
9
Q
What does meiosis produce?
A
4 genetically different gametes (haploid - 23)
10
Q
How many times does the cell divide in meiosis?
A
twice
11
Q
How many times does the cell divide in mitosis?
A
once
12
Q
Where does mitosis take place in a plant?
A
root tips and shoots
13
Q
Where does meiosis take place?
A
Testes and ovaries - to produce sex cells
14
Q
How do you use a microscope?
A
Turn on lamp,
set objective lens to lowest setting,
look through eyepiece lens,
adjust focusing wheel
15
Q
What can be added to the root tip to make chromosomes more visible?
A
Any stain, iodine
16
Q
How is a heterozygous person affected by a disease?
A
They are a carrier
17
Q
How is a homozygous dominant person affected by a disease?
A
They are unaffected
18
Q
How is a homozygous recessive persona affected by a disease?
A
They are affected and have the disease
19
Q
What is cell differentiation?
A
Where cells become specialised
20
Q
Why do cells differentiate?
A
To perform specific functions
21
Q
What is a stem cell?
A
An undifferentiated cell which is not yet specialised
22
Q
What is an adult stem cell?
A
A stem cell which can only differentiate into a specific number of related cell types
23
Q
What is an embryonic stem cell?
A
A stem cell which can differentiate into any type of cell
24
Q
Where does cell differentiation take place?
A
Meristem of plants, anywhere in animals
25
What is cell elongation? Where?
Where plant cells become longer as they grow, this can occur anywhere in the plant
26
What is the circulatory system specialised to do?
Transport substances, defend the body and regulate temperature
27
What is the excretory system specialised to do?
Remove waste products and unwanted substances, regulate water content of body
28
What is the muscular system specialised to do?
to bring about movement
29
What is the Nervous system specialised to do?
Respond to internal and external stimuli and conditions, carry messages for the body to work together
30
What is the Skeletal system specialised to do?
To bring about movement, produce blood cells and protect internal structures
31
What is the Respiratory system specialised to do?
To deliver oxygen for respiration and remove waste
32
What is the reproductive system specialised to do?
Bring about fertilisation to produce offspring
33
What is the Palisade mesophyll specialised to do?
To carry out photosynthesis
34
What is the spongy mesophyll specialised to do?
Allow gases to circulate, to carry out photosynthesis
35
What are the guard cells specialised to do?
Open and close stomata to control exchange of gases
36
What are sieve tubes specialised to do?
Transport products of photosynthesis
37
What are companion cells specialised to do?
Provide energy required for transport of substances in sieve tubes
38
What are xylem vessels specialised to do?
transport water and dissolved minerals up plant
39
What is the meristem specialised to do?
Produce new cells as they divide
40
What is cancer?
A non-communicable disease caused by undifferentiated cells growing uncontrollably in mitosis
41
What is a tumor?
A group of cancerous cells
42
What is a benign tumor?
Grows slowly, easily removed, doesn't spread
43
What is a malignant tumor?
Grows quickly, spreads to body
44
What is carcinogen?
The chemical causing cancer
45
What are some risk factors for cancer?
Genetics,
smoking, exposure to ultraviolet,
diet,
alcohol
46
What is the structure of DNA?
Double helix,
sugar phosphate backbone,
complementary bases
47
What are the bases of DNA and which are they complementary to?
Adenine - Thymine
| Cytosine - Guanine
48
What are DNA bases held together by?
Weak hydrogen bonds
49
What is each momomer of DNA called?
A nucleotide
50
What is a gene?
A particular sequence of base codes for a protein
51
What is a genotype?
The alleles than an organism has
52
What is a phenotype?
The characteristics of an organism based off of their genotype
53
What is a prokaryote?
Where there is no membrane-bound nucleus so DNA is free in cytoplasm as chromosomes or plasmid DNA`
54
How do you extract DNA from a fruit?
1) blend fruit (strawberries or kiwis) with saltwater to break apart cell walls - salt will make DNA stick together
2) pass liquid through a sieve and collect 'fruit soup'
3) Add washing up liquid to rupture cell membrane
4) add protease to uncoil DNA
5) Add ethanol to slow down enzymes
6) collect DNA by winding it round a stick
55
Why do we use ethanol in DNA extraction?
to precipitate the DNA
56
How have bacteria evolved to become resistant to antibodies?
1) Initial resistance caused by random mutations in DNA
2) This protects the bacteria from antibodies - normal bacteria are killed so only resistant bacteria are left
3) Resistant bacteria reproduce so population becomes only bacteria which are resistant to antibodies
57
How would we slow down development of resistant bacteria?
Avoid unnecessary use of antibiotics and always complete the full course
58
What is resistant bacteria an example of?
Natural selection
59
How do tools provide evidence for evolution?
1) More complex tools are more recent because species have become more intelligent - as proved by growing cranial capacity
2) Older tools will be found in deeper layers of rock, newer tools in more shallow layers
60
When was 'Ardi' found?
4.4 million years ago
61
What species is 'Ardi'?
Ardipithecus Ramidus
62
What were some features of 'Ardi'?
- Ape like big toe
- structure of feet suggests tree climbing
- long arms and short legs
- brain size about the same size of a chimpanzee
- Walked upright
63
When was 'Lucy' found?
3.2 million years ago
64
What species is 'Lucy'?
Australopithecus Afarensis
65
What were some features of 'Lucy'?
- Arched feet
- size of arms and legs more human-like than Ardi
- walked upright
66
What is the order of species?
Ardipithecus, Australopithecus, Homo species, homo sapiens
67
What is natural selection?
Those with the characteristics which make them better adapted in their environment have a better chance of surviving and are more likely to breed successfully, passing on their characteristic.
68
Why does genetic variation occur?
A difference in alleles (versions of genes) and mutations.
69
What is selection pressure?
How an organisms chance of surviving is affecting because of predation, competition and disease
70
How can drought-resistant crops be produced?
Cross-pollinating two plants which have a genetic variation to be drought resistant and growing these seeds in drought conditions will cause them to be drought resistant and adapted to these conditions. Choose offspring and repeat this process over several generations
71
What are the steps of genetic engineering?
1) Restriction enzymes are used to isolate the required gene leaving it with sticky ends (short sections of unpaired bases)
2) A vector, which is usually a bacterial plasmid or a virus, is cut by the same restriction enzyme leaving it with corresponding sticky ends.
3) The vector and the isolated gene are joined together by ligase enzyme.
4) The vector inserts the gene into required cells.
5) The genes are transferred to animal, plant or microorganism cells, during early development, which allows them to develop with the desired characteristics.
72
What are benefits of genetic engineering?
not weather dependent,
faster,
greater yield produced
73
What are negatives of genetic engineering?
May not be effective,
| concerns over genetically modified organisms entering environment and causing harm
74
What is a communicable disease?
A disease which can be spread (through bodily fluids, the air, water or being bitten by an insect)
75
What is the life cycle of a communicable disease?
1) Infect host
2) reproduce or replicate
3) spread
76
What is a vector?
An organism that spreads disease
77
What are the features of a viruses?
Not alive,
Made up of short length genetic material surrounded by a protein coat,
Cannot be treated by antibiotics,
Makes new viruses by DNA replication not reproduction
78
What are some examples of viral diseases?
HIV, Covid, Measels, chicken pox
79
What are the features of a bacterial disease?
Prokaryotic,
killed by antibiotics,
have a flagellum,
preventable by a vaccine
80
What are some examples of Bacteria?
Tuberculosis, Cholera, Salmonella
81
What are the features of Protists?
Single cell organisms,
Spread by vectors,
No vaccine
82
What are some examples of diseases caused by protists?
Malaria - caused by plasmodium
83
What are the features of fungi?
Multicellular,
spread easily,
tend to live in warm and moist places on skin
84
What are some examples of fungal diseases?
Athletes foot and ringworm
85
Tuberculosis: Spread, symptoms and prevention
Bacteria in droplets in air - sneezing and coughing.
Coughing blood specked mucus, fever, weight loss.
Prevented by vaccinations and good hygiene
86
Cholera: Spread, symptoms and prevention
Spread by disease in dirty water
Symptoms include thirst, vomiting, severe diarrhoea
Prevented by sterilising water and not drinking dirty water
87
Malaria: Spread, symptoms and prevention
Spread by a vector - mosquitoes
Symptoms include fever, weakness and sickness
Prevented by taking anti-malarial drugs and taking measures to stop getting bitten by mosquitoes (nets, covering up...)
88
Chalara Ash Dieback: Spread, symptoms and prevention
- affects ash trees -
Spread in air because of fungus
Symptoms include lesions (damages of tissues) on trunk and branches and leaves dying
89
What are non-communicable diseases?
Diseases which cannot be spread and develop due to inherited genes
90
What are some examples of non-communicable diseases?
Cystic Fybrosis - where too much mucus is produced, affecting the lungs
Haemophillia - excessive bleeding caused by blood not clotting properly
91
In What ways can lifestyle affect non-communicable diseases?
Diet and exercise - type 2 diabetes
| smoking - cancer, CVD and lung disease
92
What is a pathogen?
A microorganism that can cause disease
93
How are Viruses spread?
bodily fluids
94
How are bacterial diseases spread?
direct contact
95
How are protists spread?
Via a vector
96
How do fungi spread?
they spread microscopic spores which can be inhaled or made in contact with the body
97
What are enzymes?
Biological catalysts which speed up chemical reactions without being used up
98
What is the lock and key mechanism?
Enzymes have an active site with a complementary shape to a specific substrate. It will bond with the substrate to form products. If the substrate's shape doesn't match the active site then the reaction won't be catalysed.
99
How does temperature affect the activity of an enzyme?
Increasing temperature increased the rate of reaction
Until it gets to hot and breaks the bonds, changing hte active site of the enzyme so it is no longer complementary to the substrate and the reaction stops (it becomes denatured)
100
How does pH affect the activity of an enzyme?
Enzymes have an optimum pH where activity is fastest. If too high or low the e enzyme will become denatured
101
How does substrate concentration affect the activity of an enzyme?
Higher concentration causes a faster rate of reaction as enzymes are more likely to react with a substrate molecule. If too high adding more makes no difference as active site will become full.
102
How is starch broken down?
Amylase breaks it down into smaller sugars like maltose. Maltose molecules are broken down by maltase into glucose
103
Where is Amylase produced?
Salivary glands, pancreas and small intestines
104
How are proteins broken down?
Protease breaks them down into amino acids
105
Where is protease produced?
Stomach, pancreas and small intestines
106
How are fats broken down?
By lipase
107
Where is lipase produced?
the pancreas, mouth, and stomach.
108
Why do we use saltwater in DNA extraction?
Salt makes DNA stick together
109
Why do we use protease in DNA extraction?
To uncoil the DNA
110
Why do we use washing up liquid in DNA extraction?
To rupture cell membrane
