Question 1
1
Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater lakes of Alaska before migrating to marine waters. Their first months in marine waters are spent foraging and growing near the shore line. They then move to offshore regions of the North Pacific Ocean for 2 to 3 years. The graph shows fork length frequency of juvenile O. nerka caught during their first months in marine waters in autumn 2008 and ocean age one O. nerka caught 15 months later during winter 2009 in the North Pacific Ocean.
9 marks
Question 1(e)
1(e)
Using the data, suggest one reason for the relationship between protein content and fork length.
Mediumstructured1 marks
Answer
growth is a result of incorporating protein / larger fish have more protein/more muscle/more cells
Question 1
1
Low protein diets are a widespread problem in the developing world. A low protein diet in a pregnant mother could affect a developing fetus. Other mammals are used as a biomedical model for energy metabolism and malnutrition in humans. In an experiment to study the effect of protein levels in the diet, pregnant mammals were fed diets with different ratios of protein to carbohydrate: - low protein : high carbohydrate (LP), - adequate protein: adequate carbohydrate (AP), - high protein : low carbohydrate (HP). The table shows the average birth mass of the offspring and the body mass gain of the mother during the pregnancy. The concentration of several substances in the plasma of the mothers was also recorded. LDL (low density lipoprotein) is considered "bad cholesterol" and HDL (high density lipoprotein) is considered "good cholesterol".
0 marks
Question 1(d)
1(d)
Explain the low birth mass of offspring born to mothers who were fed the LP diet.
Mediumstructured2 marks
Answer
a. lack of essential amino acids to form protein; b. not enough protein for growth; c. not enough amino acids/protein to form muscle/tissues; d. low protein may affect production of enzymes;
Question 1(e)
1(e)
In many societies doctors may recommend an HP diet for pregnant humans. Using the data, evaluate this recommendation.
Hardstructured3 marks
Answer
(the data does not support the recommendation): a. as HP has the highest level of plasma urea which could be toxic; \(\left.\begin{array}{l}\text { b. HP has a high level of LDL/bad cholesterol and a low } \\ \text { level of HDL/good cholesterol which could lead to coronary } \\ \text { heart disease; }\end{array}\right\} \begin{aligned} & \text { (accept high ratio } \\ & \text { of LDL:HDL) }\end{aligned}\) c. HP produces a high level of glucose (compared to AP) which could lead to diabetes; d. HP produces a low birth weight (compared to AP) which may affect development / OWTTE; (the data does support the recommendation): e. the mother has a similar weight gain to AP thus avoiding health problems;
Question 1
1
Edible insects have been a part of traditional human diets in many countries. For example, crickets are insects commonly eaten in Asia and Africa. Many studies have looked at the prospects of raising insects on a commercial scale for direct human consumption as food or indirectly by feeding insects to farm animals. One factor to consider is which organisms are most efficient at converting the feed they eat into animal protein that can be consumed. A study compared the percentage of mass that was edible in two common farm animals and in crickets.
12 marks
Question 1(b)
1(b)
The yellow mealworm (Tenebrio molitor) is native to temperate regions of the world and has been studied as a possible means of producing food in countries with that type of climate. The amino acid content of yellow mealworms and cattle was analysed. The table shows the results for seven amino acids that are required in the human diet.
2 marks
Question 1(b)(i)
1(b)(i)
Distinguish between the amino acid contents of yellow mealworms and cattle.
Mediumstructured1 marks
Answer
a. mealworms have more isoleucine/leucine/valine than cattle b. cattle have more lysine/methionine/phenylalanine/threonine c. the total proportion of these amino acids is «slightly» greater in cattle (188 to 176)
Question 1(b)(ii)
1(b)(ii)
Predict, with a reason, whether the amino acid composition of yellow mealworms or cattle is more suitable for a human diet. The environmental impact of producing protein from mealworms was compared with the impact of producing traditional protein sources. The graphs show the greenhouse gas production (global warming potential) and land use due to the production of 1 kg of protein from mealworms, chickens and cattle.
Mediumstructured1 marks
Answer
a. cattle as they are more closely related to humans b. cattle as they are more likely to have proteins with a similar amino acid composition to humans c. cattle as they contain a «slightly» higher proportion of «essential» amino acids required in human diet (188 to 176) OWTTE.
Question 3
3
Which is an effect of protein denaturation? A. The order of amino acids is changed when the protein overheats. B. The bonds between amino acids are broken by condensation. C. Parts of the protein become linked together by hydrolysis. D. The three-dimensional structure of the protein is altered.
Easymcq1 marks
Answer
D
Question 3
3
How are amino acids joined together to form a dipeptide? Single bond between a carbon and a hydrogen Hydrolysis reaction forming a hydrogen bond Anabolism forming a double bond Condensation reaction forming a peptide bond
Easymcq1 marks
Answer
D
Question 3
3
The table shows some essential and non-essential amino acids. What is a valid conclusion for an amino acid in the table? Lysine is synthesized by the human body. Alanine can only be obtained from food. Glycine is not used in the human body. Valine must be supplied in the diet.
Easymcq1 marks
Answer
D
Question 4
4
What must vegans ensure when they plan their diet? Higher protein consumption than meat-eaters Sufficient quantities of all essential amino acids are consumed Only proteins with all 20 amino acids are consumed Higher fat consumption than meat-eaters
Easymcq1 marks
Answer
B
Question 4
4
Diagrams of three different proteins, X, Y and Z , are shown. Which row describes the structure of each protein shown?
Mediummcq1 marks
Answer
B
Question 4
4
Myoglobin is a globular protein in which nearly all the non-polar R-groups point towards the inside of the molecule. The outside surface contains all the polar R-groups. What can be deduced from this? Disulfide bonds occur on the inside. Hydrogen bonds form with water on the outside. Ionic bonds form with water on the outside. Covalent bonds occur on the inside.
Mediummcq1 marks
Answer
B
Question 4
4
Which row correctly matches the level of structure of a protein molecule with the bonds that stabilize it?
Hardmcq1 marks
Answer
C