Practice Paper 1A (SL IB Biology)

Which of the following drawings best represents the structure of a section of DNA?

A prokaryotic cell has a diameter of 1 µm. The cell is magnified ×50 000 by an electron microscope.

In the electron micrograph that is produced by the electron microscope, what is the diameter of the prokaryotic cell?

Which set of observations would indicate that a student is observing a eukaryotic cell?

Which is the correct definition for a species according to the biological species concept?

Which of the following statements about selective breeding is correct?

What is the most important requirement for speciation to occur?

Melanin is a dark pigment produced in the cells; higher melanin production results in an organism's darker colour.

It has been noted that melanistic peppered moths have become more common than non-melanistic individuals in industrialised parts of the UK where air pollution has increased.

Air pollution kills organisms, called lichens, that grow on the bark of trees. Areas with clean air have more lichen resulting in trees of a lighter colour compared to polluted areas where lichen are killed, causing tree trunks and branches to appear darker.

Which of the following is not a reason for the evolution of melanism in peppered moths?

Which of the statements about conservation is correct?

The diagram below shows several different biological molecules (Q, R, S and T).

Which row of the table below correctly identifies some of the products of hydrolysis of the molecules above?

Which is the correct reason that cellulose passes through the gut undigested?

Amino acids consist of oxygen, hydrogen, carbon and nitrogen atoms. The diameter of each atom when bonded to another atom is shown in the table below.

Using the figures in the table, the approximate length of one amino acid is 0.7 nm, as shown below.

What would be the approximate length of a dipeptide of this amino acid after a condensation reaction has occurred?

What is the difference between simple diffusion and facilitated diffusion?

The cells of bacteria are on average 1-5 µm long, whereas human cells are on average 100 µm in diameter. 

What is the main limiting factor preventing the bacterial cells from growing to the same size as human cells? 

An alveolus has several features to allow efficient gas exchange.

Which row of the table below matches each feature of gas exchange to the correct label on the alveolus?

The diagram shows a potometer set up to measure the rate of transpiration in a piece of cut plant. 

For a potometer with a cylindrical capillary of the internal diameter of d mm, the bubble was measured to travel h mm in an experimental time of s seconds. 

Which is the correct formula to calculate the rate of transpiration (as a volume of water uptake per unit time) in this experiment?

A group of scientists studied the distribution of an invertebrate species on a series of sandy beaches. Their results are shown in the graph.

Which of the statements about the data is correct?

Which of the following statements about ecological niches is correct?

When investigating the rate of reaction of the enzyme lipase on the hydrolysis of triglycerides, the pH must be maintained to prevent the lipase denaturing.

Why might fluctuations in pH occur?

The graph below shows the energy changes during a reaction.

What effect would adding an enzyme have on the energy changes of the reaction?

The following graphs show the absorption spectrum for chlorophyll a and the action spectrum showing the relative rate of photosynthesis at different wavelengths of light.

Why do the graphs look different?

The image below shows a petri dish viewed from above. A lawn of bacteria is growing across the whole surface of the agar. 

Different antibiotics, X and Y were applied to the agar before inoculating it with bacteria. Both antibiotics were applied to the discs of filter paper at the same concentration. 

The plates were then incubated for 24 hours at 25°C. Zones of inhibition (areas of the dish with no bacterial growth) are shown on the diagram.

After growth, the following results were obtained. 

How many times more effective was antibiotic Y versus antibiotic X in this study? 

The pneumococcal conjugate vaccine (PCV13) provides protection against infection caused by the bacterium Streptococcus pneumoniae. The graph shows the number of cases of invasive pneumococcal disease (IPD) caused by antibiotic resistant S. pneumoniae before and after the introduction of PCV13.

Which statement correctly explains the number of cases of IPD caused by antibiotic resistant S. pneumoniae after the introduction of PCV13?

A chi-squared test was carried out to test for association between species A and species B.  The results of the chi-squared test are given below. 

Results of chi-squared test:

Critical values table:

What can be concluded from the chi-squared test for association carried out to test for association between species A and species B?

The graph shows changes in percentage cover of four plant species on a sand dune ecosystem over 500 years.

Which of the following explanations cannot be supported using the information in this graph.

Which row of the table correctly identifies an observation of food chains and the theory used to explain that observation?

When DNA polymerase adds a new nucleotide to a growing DNA strand, which part of the last nucleotide does it form a bond with?

The pedigree chart below shows the inheritance of Tay-Sachs disease which is an autosomal recessive trait, characterised by neurological problems caused by the death of nerve cells. 

In the pedigree chart, a filled in circle or square means the individual is affected and shows the genetic condition.

What is the probability that individuals 3 and 4 will have another child with Tay-Sachs disease?

A one year old child displays fatigue and excessive thirst over a period of time. A urine test reveals the presence of glucose.

Which of the following would be the most likely diagnosis?

Which of the following is not true about mesocosms?