Biology Paper 1 Flashcards
1
Q
How many sub-phases are there in interphase?
A
3
2
Q
How do singles called organisms get rid of their waste?
A
It diffuses across the membrane
3
Q
When, during the cell cycle, does semi-conservative replication happen?
A
S phase
4
Q
Which phase of mitosis do chromosomes get pulled apart?
A
Anaphase
5
Q
How does bacteria divide?
A
By binary fission
- > circular loop of DNA replicates and move to opposite ends of cell
- > plasmid replicates
- > cytoplasm divides to form two daughter cells with each one having a single copy of circular DNA
6
Q
What is binary fission?
A
Asexual reproduction of single cell organism eg bacteria
7
Q
How many stages of mitosis?
A
4
7
Q
What happens during G1 of interphase?
A
Organelles are made
9
Q
Which stage of mitosis does chromosome condensing occur?
A
Prophase
9
Q
What system within the body carries the waste around?
A
Circulatory
11
Q
What is the First stage of mitosis?
A
Prophase
12
Q
What do efficiency of gas exchange depend on? (3)
A
High surface area
Short diffusion pathway
High concentration gradient
13
Q
How do insects carry out gas exchange?
A
- Air enters through holes called spiracles
- oxygen diffuses down the concentration gradient along the trachea
- trachea are closely surrounded by cells
- oxygen diffuses into cells
- ventilations helps to maintain a high concentration gradient
14
Q
How do insects prevent some water loss?
A
- body covered in waxy cuticle that reduces evaporation
- insects can close their spiracles
15
Q
How does a fish carry out gas exchange?
A
- filaments and lamellae have a big surface area which increase efficiency of diffusion
- thin epithelium means that there’s a short diffusion distance
- countercurrent flow (of blood and water) maintains a high concentration gradient as water is always next to blood with a lower concentration of oxygen
- circulation of blood replaces blood that is saturated with oxygen
- Ventilation of water replaces water low in oxygen
16
Q
What is the process of phagocytosis?
A
Engulfing of pathogens
17
Q
Gases diffuse into leaves via what structure?
A
Stomata
18
Q
What organ do insects use for gas exchange?
A
Tracheae
19
Q
What is the main exchange surface in a leaf?
A
Mesophyll layer
20
Q
How does air enter the insect?
A
Via the spiracles
21
Q
What tissue is the diaphragm made from?
A
Muscle
22
Q
What genetic effect occurs when a small number of member of a population more to a new area?
A
Founder effect
23
Q
What causes genetic diversity within a species?
A
Alleles
24
Q
How many chromosomes does a haploid human cell contain?
A
23
25
What impact does genetic bottleneck have on the genetic diversity of a population?
It decreases it
26
What colour indicates a positive result in the bitter test?
Purple
27
What makes a enzyme highly specific?
It’s tertiary protein structure
28
What is the test for proteins known as?
Biuret test
29
When starch and amylase are mixed in the presence of iodine solution, the blue-black colour rapidly disappears. This is due to the formation of which molecule?
Maltose
30
What do you get when you hydrolyse starch?
Maltose
31
*Differences between eukaryotic DNA and prokaryotic DNA
Prokaryotic DNA doesn’t have Histones
| Prokaryotic cells have circular DNA whereas eukaryotic cells have double helix
32
*When staining the chromosomes some parts of the chromosome have more stain than others causing them to appear striped. Suggest why
The dye stains regions of chromosomes that are rich in the base pairs Adenine (A) and Thymine (T) producing a dark band.
33
*Define homologous chromosomes
A pair of matching chromosomes- each chromosome contains the same genes but may have different alleles
34
*Define species richness
The number of different species in a community, a measure of biodiversity
35
*Function of 2 enzyme involved in DNA replication
DNA polymerase- joins together nucleotides on a new strand of DNA
DNA helicase- breaks hydrogen bonds between two polynucleotides DNA strands
36
*Why E-S complex increase rate of reaction
Lowers the activation energy so less energy needed to start reaction
37
*How is lactose formed and how it forms a glycoprotein? (4 marks)
- galactose
- and glucose
- condensation reaction
- glycosidic bonds
- Proteins modified in the Golgi apparatus and glycoprotein formed when a carbohydrate such as lactose is added to protein
38
*Similarities and differences between the structures of Triglyceride and phospholipids
Similarities:
-both have glycerol
-both have fatty acids
- both store energy
Differences:
- phospholipids has a phosphate and 2 fatty acids but triglycerides has 3 fatty acids
- triglycerides are not water soluble but phospholipids are water soluble molecules
39
*What is the structure of a amino acid?
```
Variable group (R)
Amino group (H2N)
Carboxyl group (COOH)
Carbon atom
Hydrogens atom
```
40
Effect of exercise on ventilation
Increase tidal volume
Increase breathing rate
Increase pulmonary ventilation
Increase oxygen consumption
41
Describe how a phagocyte destroys bacterium (5 marks)
In order
1. Phagocytes attach themselves to the surface of the bacterium;
2. Engulf the bacterium to form a vesicle / phagosome;
3. Lysosomes move towards the vesicle and fuse with it;
4. Hydrolytic enzymes / lysozymes break down / digest bacterium;
5. Soluble products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte;
6. Waste products leave the phagocyte by exocytosis / antigens from the bacteria are displayed on phagocyte cell membrane;
42
Explain why T cells are effective against viruses (2 marks)
T cells destroy virus infected cells;
| viruses need living cells to reproduce;
44
Describe the principles and limitations of using a transmission electron microscope to investigate cell structure (5 marks)
Principles:
1. Electrons pass through / enter (thin) specimen;
2. Denser parts absorb more electrons;
3. (So) denser parts appear darker;
4. Electrons have short wavelength so give high resolution;
Principles: Allow maximum of 3 marks
5 max
Limitations:
5. Cannot look at living material / Must be in a vacuum;
6. Specimen must be (very) thin;
7. Artefacts present;
8. Complex staining method / complex / long preparation time;
9. Image not in 3D / only 2D images produced.
45
Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria from a suspension of animal cells (5 marks)
Any Five from:
1. Accept suitable method of breaking open cells.
2. Filter to remove (large) debris / whole cells;
2. Reject removes cell walls.
3. Use isotonic solution to prevent damage to mitochondria / organelles;
3. Ignore to prevent damage to cells.
4. Keep cold to prevent / reduce damage by enzymes / use buffer to prevent protein / enzyme denaturation;
5. Centrifuge (at lower speed / 1000 g) to separate nuclei / cell fragments / heavy organelles; 5. Ignore incorrect numerical values.
6. Re-spin (supernatant / after nuclei / pellet removed) at higher speed to get mitochondria in pellet / at bottom.
M2.(a) Any
1. Cell homogenisation to break open cells;
6. Must have location
Reject ref to plant cell organelles only once
46
From a sample of epithelial cells, explain why some cells had twice the amount of dna than others
As the ones with twice the amount of dna were in late interphase and the other ones were in early interphase/dna had not replicated yet
