Mock Exam Set 1 - Paper 3

[Maximum mark: 5]

Cancer studies have shown that many tumours have abnormal patterns of aerobic respiration, showing increased levels of glycolysis and lower levels of oxidative phosphorylation, even in the presence of high oxygen levels. A breast cancer cell line (MDA-MB-231) shows variable protein expression of complex III in the electron transport chain compared to normal breast tissue.

1. Outline the role of the complexes in the electron transport chain. [2]
   

2. Predict, with a reason, what would happen to the levels of oxidative phosphorylation in the non-cancerous cells if they were treated with an inhibitor of glycolysis. [1]
   

3. The researchers concluded that downregulation of complex III in breast cancer cells is a cause of breast cancer. Evaluate this conclusion. [2]
   

[Maximum mark: 5]

A study has been conducted on the effect of hormonal contraception pollution on the mating calls of the adult male African clawed frog (Xenopus laevis). The spectrogram shows the frequency and volume of clicks (mating call) of control X.laevis and those exposed to oestrogen.

The graph shows the average duration of the X. laevis mating calls when exposed to the hormone oestrogen.

1. Describe the effect of oestrogen on the rate of clicks and on the duration of the mating call. [2]
   

2. Explain why it is important to have the X.laevis control group. [1]
   

3. Identify the independent variable in this study. [1]
   

4. Predict the reproductive success of X.laevis exposed to 29.6 ng/L of oestrogen. [1]
   

[Maximum mark: 5]

Creatine is a naturally occurring chemical produced in the body which supplies energy to muscles. It’s also a supplement used widely in the fitness industry to reduce recovery times and improve athletic performance.

Creatine is broken down into creatinine which is toxic in high concentrations. A study was conducted on the effect of creatine supplementation on the creatinine concentration in the urine. Urine samples were collected from humans, and the creatinine concentration was measured.

The results from the study were used to make up corresponding creatine solutions to mimic the urine samples. These creatine solutions were then given to students to analyse. The specific gravity of each sample was measured using a hydrometer, a small graduated float used to compare the density of a liquid between two samples.

1. 1. Other than protein, state the name of one substance that can be detected in urinary tests. [1]
      

   2. High creatinine concentrations in the blood can lead to kidney failure. List two possible treatments for kidney failure. [1]
      

2. Calculate, as a percentage, how much greater the urine sample specific gravity with 10g of supplemental creatine intake was compared to that with 5g of supplemental intake. [1]
   

3. Describe TWO reasons why mice were used in this experiment and not humans. [2]