AS & A Level Biology - 9700 Paper 1 2020 Summer Zone 2

What is the definition of the resolution of a light microscope?

The electron micrograph shows a type of virus at a magnification of \( \times 30\,000 \).

What is the length of the virus?

Which row correctly shows a feature of a cell structure?
[Table_1]

Four students were asked to match the function with the appearance of some cell structures in an animal cell.
The functions were listed by a number.
1. organises microtubules to produce the spindle during cell division
2. synthesis of polypeptides
3. packaging of hydrolytic enzymes that will remain in the cell
The appearances were listed by a letter.
V. membranes which surround an enclosed inner cavity
W. non-membrane bound, spherical structures
X. a double membrane with many pores
Y. non-membrane bound, cylindrical structures
Z. membrane-bound sacs, arranged as a flattened stack
Which student correctly matched the numbered function with the appearance of the cell structure?
[Table_1]

The features of some cells and cell structures that make ATP are listed.
1. has outer boundary membrane and folded inner membrane
2. has peptidoglycan cell wall outside an outer boundary membrane
3. has a double boundary membrane and stacks of inner membranes
Which row identifies these components?
[Table_1]

Mitochondria are thought to have evolved from prokaryotic cells that were ingested by an ancestral cell.
Which feature have these prokaryotes lost during their evolution into mitochondria?

A student carried out the Benedict's test on a sample and got a negative result. What should the student do to confirm there are no sugars present in the sample?

The diagrams show three hexoses.

In which carbohydrates do these three hexoses occur?

The diagram shows part of the chemical structure of a naturally occurring polysaccharide.
What types of glycosidic bonds are present?

What is the maximum number of water molecules produced when a triglyceride is synthesised?

What occurs during the formation of a peptide bond between two amino acids?

The diagram represents roles of water in living organisms.

Which roles are dependent upon hydrogen bonds between water molecules?

The diagram shows a metabolic pathway.

What would be the effect of adding a small amount of a non-competitive inhibitor of enzyme 2?

Two enzymes are added to a solution containing a low concentration of a substrate that they can both use.
Which statement is correct?

The diagram shows the fluid mosaic model of membrane structure.
Structures 1, 2, 3 and 4 are types of molecule.



Which types of molecules are always identical?

What is the role of G protein in cell signalling?

When a small quantity of phospholipid is added to a test-tube of water and then shaken vigorously, an emulsion is formed by small droplets called liposomes.
Which diagram shows the arrangement of phospholipid molecules in a cross-section of a liposome?

What are the features of facilitated diffusion?
1. It uses protein channels in the membrane and is driven by the energy from ATP.
2. It moves molecules from regions of higher concentration to lower concentration and is driven by the kinetic energy of the molecules which are diffusing.
3. It uses protein channels in the membrane, and the maximum rate of diffusion depends on the number of these channels.

Which description of chromosome structure is correct?

Which processes involve mitosis?

A drug has been developed to treat certain types of cancer. It prevents mitosis by binding to the spindle and preventing sister chromatids being separated and moving to opposite poles of the cell.

The photomicrograph shows cells in different phases of mitosis.

What represents the stages of mitosis that will be able to occur in a cell which is entering prophase when treated with this drug?

Some viruses have single-stranded DNA as their genetic material. This DNA molecule has to be folded to fit in the protein coat.
Which statements about single-stranded DNA are correct?
1 Single-stranded DNA cannot replicate semi-conservatively.
2 If only the percentage of cytosine is known, then the percentage of guanine can be calculated, but the percentage of adenine and thymine cannot be calculated.
3 Hydrogen bonds may be present within the DNA molecule.

How many statements are true for semi-conservative replication of DNA in a eukaryotic cell?
1. The process takes place in the nucleus.
2. Adenine will line up against uracil on the complementary strand.
3. Each new molecule will contain one strand of the original molecule.
4. If the original molecule contained 40% guanine each new molecule will contain 20% guanine.

Part of the nucleotide sequence of an mRNA molecule is shown, with spaces between the codons.

CAG UAC AGC AAU CUA UAA

The translation of the codons is provided.

[Table_1]

External factors change the rate of transpiration, which also affects the water potential gradient of cells in the leaf.
Which combination is correct?
[Table_1]

The photomicrograph shows a transverse section through a leaf.
Which features of a xerophytic leaf are visible in this section?
1 sunken stomata
2 two layers of epithelium
3 thick cuticle
4 small surface area to volume

Which changes occur as carbohydrates move out of a root cell into a phloem sieve tube?
[Table_1]

The photomicrograph shows three white blood cells labelled X, Y and Z.

Which row correctly identifies these cells?
[Table_1]

The graph represents data on blood vessels and blood flow.
Which row correctly identifies the curves?

Which components of blood are present in lymph?
[Table_1]

What correctly describes the significance of the increase of the red blood cell count of humans who move from living at low altitude to high altitude?

Which structures of the human gas exchange system are supported by cartilage? [Table_1]

Carbon monoxide, nicotine and tar are components of tobacco smoke. Which row correctly describes their effect on a smoker’s body? [Table_1]

Which statements about chronic obstructive pulmonary disease (COPD) are correct?
1. The disease can often be reversed by treatment.
2. The patient's symptoms normally do not change.
3. The patient is normally over 30 years old.
4. The patient coughs frequently, producing a lot of mucus.

Which of these causative agents of disease can be transmitted by droplet infection?
1. Vibrio
2. Mycobacterium
3. Morbillivirus

The table compares total antibiotic use (X) and the percentage of antibiotic-resistant pneumonia cases (Y) in five countries. [Table_1]
What is supported by the data?

Which statement about the development of resistance to antibiotics in bacteria is correct?

A blood cell count can indicate how many white blood cells there are in the blood.
Where else in the body are white blood cells found?
1 bone marrow
2 lymph
3 lungs

Myasthenia gravis is a disease that results from the immune system failing to distinguish between self and non-self. Antibodies bind to a component of the junctions between a muscle and its nerve.
What correctly describes Myasthenia gravis?

A monoclonal antibody, specific for a virus, was treated with an enzyme to break the bonds between the variable and constant regions. The separated variable and constant regions were then added to cells infected with the virus. Which statements are correct?
1. The constant regions would bind to different parts of the virus antigens.
2. The viruses could be engulfed by phagocytes if they were present.
3. The variable regions would all bind to the same part of the virus antigens.