AS & A Level Biology - 9700 Paper 1 2010 Winter Zone 2

Which steps are needed to find the actual width of a xylem vessel viewed in transverse section using a ×40 objective lens?
1. Convert from mm to μm by multiplying by $10^{-3}$.
2. Calibrate the eyepiece graticule using a stage micrometer on ×10 objective lens.
3. Measure the width of the xylem vessel using an eyepiece graticule.
4. Multiply the number of eyepiece graticule units by the calibration of the eyepiece graticule.

A specimen is viewed under a microscope using green light with a wavelength of 510 nm. If the same specimen is viewed under the same conditions, but using red light with a wavelength of 650 nm instead, what effect will this have on the magnification and on the resolution of the microscope?
[Table_1]

Which cell organelle does not contain nucleic acid?

The diameter of living cells varies considerably.
The typical diameters are:
a eukaryote, such as a white blood cell $1.5 \times 10^1 \mu\text{m}$
a prokaryote, such as $\textit{Streptococcus}$ $7.5 \times 10^2 \text{nm}$
Use these measurements to find the maximum number of each cell type which could fit along a line 1 cm long.
[Table]

Cells consist of a number of different components. Which row shows the components present (✓) in both a prokaryotic and eukaryotic cell? [Table_1]

The diagram shows part of a carbohydrate molecule.

If all the 1,4 glycosidic bonds in this molecule are hydrolysed, how many water molecules will be used and how many separate glucose molecules will be produced?

A peptide bond is formed between atoms of which two elements?

Which features affect the tensile strength of collagen?
1. the helical structure of collagen chains
2. the small R group of the amino acids in collagen
3. the insoluble nature of collagen
4. the covalent bonds between collagen molecules

An amino acid can be represented as where R represents a variable side chain. Which is not a possible side chain?

When red cells leave the lungs, haemoglobin is 98% saturated.
How many molecules of oxygen will be carried by the majority of haemoglobin molecules?

A fixed volume of the enzyme catalase was added to a fixed volume of hydrogen peroxide solution. The diagram shows how the rate of the reaction changed over the course of the reaction.
Why did the actual rate of reaction decrease over time?

Which levels of protein structure are always involved when competitive and non-competitive inhibitors bind to enzymes? [Table_1]

The diagram shows the transport of ions across the cell surface membrane. Inside the cell there is a low concentration of sodium ions (Na^+) and a high concentration of potassium ions (K^+). Outside the cell there is a low concentration of K^+ and a high concentration of Na^+.
The carrier molecule is a pump which exchanges Na^+ for K^+ ions.

Which ionic movements are represented by the arrows?

Plant cells were immersed in solutions of different water potential and left for one hour.
Which row shows the effect of the different solutions on the plant cells?
[Table_1]

Which molecules, found in cell surface membranes, contribute to cell recognition?
1. glycolipids
2. glycoproteins
3. phospholipids

The cell cycle includes mitosis.
Which are features of \textit{nuclear} division?
1. forms cells of equal size to the parent cell
2. forms genetically identical cells
3. semi-conservative replication of DNA

In which process does mitosis not have an important role in living things?

The diagram shows the chromosomes of a typical plant cell at the metaphase stage of mitosis.

Which row describes this cell during metaphase?
[Table_1]

The table shows the percentages of bases in DNA from various types of cell.
[Table_1]
What is a valid deduction from these data?

Which row shows the correct combination? [Table_1]

A culture of bacteria had all its DNA labelled with the heavy isotope of nitrogen ($^{15}$N). A sample was taken and spun in a centrifuge.
The diagram shows the position of the DNA band at Z in the centrifuge tube.

The culture was then allowed to reproduce using nucleotides containing the normal isotope of nitrogen ($^{14}$N). Samples were taken and spun in a centrifuge after one generation and again after two generations.
In which pattern would the DNA be found after the first and after the second generations?

S and T are products of a biochemical pathway. A different enzyme, coded for by different specific genes, catalyses each step in the pathway.
[Image_1: Diagram showing pathways P to Q by enzyme 1, Q to R by enzyme 2, R to S by enzyme 3, and R to T by enzyme 4, with the corresponding genes.]
What is the possible outcome to the pathway if a mutation in gene 3 leads to an inactive enzyme?

Which processes are involved in transpiration?
1. the diffusion of water vapour from stomata
2. the mass flow of water through the xylem
3. the evaporation of water from spongy mesophyll cells
4. the evaporation of water vapour from exposed leaves

What is the main function of a companion cell in mature phloem tissue?

Water passes across leaf tissues by different routes as a result of
• differences in water potential
• the pull transmitted by cohesive forces between water molecules.

The diagram shows three routes by which water can travel.

Which row correctly identifies why water passes across leaf tissues by the different routes?

The diagram shows a transverse section of a stem. Which area is the phloem?

The diagram shows the water potential ($\Psi$) in some plant cells and in their environment.

Which statements are correct for this situation?
1. Water moves into and out of all three cells.
2. There is a net movement of water into cell 1.
3. There is no movement of water from the environment to cell 2.
4. Water moves out of cell 3 so it becomes plasmolysed.

Which of the tissue types below are present in the walls of all blood vessels?
1. collagen
2. elastic
3. endothelial
4. smooth muscle

In mammals, some carbon dioxide is transported by red blood cells in combination with haemoglobin. What is the product of this combination?

The graph shows pressure changes during a cardiac cycle. Which row correctly identifies W, X, Y, and Z?

Some babies are born with a hole between the right and left atria. These newly born babies are found to have an increased number of red blood cells. What is the reason for this increase?

Which row correctly shows the areas of the respiratory tract that contain cartilage, cilia (ciliated epithelium), goblet cells and smooth muscle? [Table_1]

In some cases where a person has lung disease, the partial pressure of oxygen in the pulmonary veins is less than the partial pressure of oxygen in the alveoli.
Which would contribute to the description above?
1. A high proportion of alveoli are collapsed and do not have enough alveolar capillaries.
2. The degree of alveolar ventilation is too low for the cardiac output supplying most of the alveoli.
3. The partial pressure of oxygen in the pulmonary arteries is lower than in the alveolar air.
4. The rate of diffusion of oxygen from the alveolar air to the surrounding alveolar capillaries is too slow.

Which of the effects listed occur as a result of inhaling both carbon monoxide and nicotine from cigarette smoke?
1. increased heart rate
2. increased risk of cardiovascular disease
3. increased risk of emphysema
4. increased risk of lung cancer

During an investigation on gas exchange, three measurements were made on four people. The efficiency of gas exchange was the same in all four people.
Which person, A, B, C or D, absorbed most oxygen during normal breathing?
[Table_1]

The data shows how the number of human deaths caused by the bacterium _Staphylococcus aureus_ has changed from 1997 to 2005.
Methicillin is an antibiotic used to treat a disease caused by _S. aureus_.
MRSA is methicillin-resistant _S. aureus_.

[Table_1]

Which statement is not supported by this data?

An enzyme hydrolyses the two heavy polypeptide chains of an antibody molecule. The hydrolysis occurs at the hinge region and breaks the antibody into three fragments. How many of these fragments are able to bind to antigens?

The diagram shows the response to a pathogen by the immune system.



Which row correctly identifies P, Q, R and S?

The diagram represents part of the nitrogen cycle.
Which process is carried out by nitrifying bacteria?

The diagram shows the flow of energy between organisms in an ecosystem. Which correctly identifies each organism in the ecosystem?