Q: A food label states that a snack contains 10 g of carbohydrates, 5 g of protein, and 8 g of lipids. What is the total energy content of the snack in kilojoules ($$\mathrm{kJ}$$)? Use the following values: carbohydrates $$=17\ \mathrm{kJ/g}$$, proteins $$=18\ \mathrm{kJ/g}$$, lipids $$=39\ \mathrm{kJ/g}.$$

$$(10 \times 17) + (5 \times 18) + (8 \times 39) = 170 + 90 + 312 = 572\ \mathrm{kJ}$$

Q: A food contains 20 g of lipids, 15 g of carbohydrates, and 10 g of protein. Calculate the total energy content in $$\mathrm{kJ}.$$

$$20 \times 39 + 15 \times 17 + 10 \times 18 = 780 + 255 + 180 = 1215\ \mathrm{kJ}$$

Question 1

A group of laboratory rats is fed a diet consisting only of pure carbohydrates, lipids, and proteins, with no additional supplements. After several weeks, the rats begin to show signs of illness and poor growth. Which of the following best explains the likely cause of these symptoms?

Accepted Answer

The diet lacks essential vitamins required for normal physiological functions.

Question 2

A patient presents with bleeding gums and slow wound healing. Which vitamin deficiency is most likely responsible for these symptoms, and what is a classic disease associated with this deficiency?

Accepted Answer

Vitamin C deficiency; Scurvy

Question 3

Which of the following foods would provide the highest energy content per gram, based on the energy values of macronutrients?

Accepted Answer

Butter, because lipids provide $$39\ \mathrm{kJ/g}$$

Question 4

A food label states that a snack contains 10 g of carbohydrates, 5 g of protein, and 8 g of lipids. What is the total energy content of the snack in kilojoules ($$\mathrm{kJ}$$)? Use the following values: carbohydrates $$=17\ \mathrm{kJ/g}$$, proteins $$=18\ \mathrm{kJ/g}$$, lipids $$=39\ \mathrm{kJ/g}.$$

Accepted Answer

$$(10 	imes 17) + (5 	imes 18) + (8 	imes 39) = 170 + 90 + 312 = 572\ \mathrm{kJ}$$

Question 5

Which vitamin group is essential for cell respiration, and what are the consequences of its deficiency?

Accepted Answer

Vitamin B group (B1, B2, B3); deficiency can cause diseases like beri-beri and pellagra

Question 6

A student is testing a food sample for the presence of starch, glucose, protein, and lipid. What is the first step in preparing the sample for these chemical tests?

Accepted Answer

Grind the food into small pieces and shake with water to extract components.

Question 7

Which of the following best describes the role of enzymes in digestion?

Accepted Answer

Enzymes catalyze the breakdown of food molecules into smaller building blocks for absorption.

Question 8

A person consumes a diet high in fruits and vegetables but low in animal products. Which vitamin deficiency are they least likely to develop, based on the information provided?

Accepted Answer

Vitamin C deficiency, because fruits and vegetables are rich sources of vitamin C.

Question 9

A patient is diagnosed with pellagra, which is characterized by dry red skin, poor growth, and digestive disorders. Which vitamin deficiency is most likely responsible?

Accepted Answer

Vitamin B3 (niacin)

Question 10

Which of the following statements about the energy content of foods is correct?

Accepted Answer

Foods high in lipids, such as butter and nuts, have a higher energy content per gram than foods high in carbohydrates or proteins.

Question 11

During digestion, which of the following best describes the fate of large food molecules?

Accepted Answer

They are broken down by enzymes into smaller molecules that can be absorbed through the gut wall.

Question 12

A food contains 20 g of lipids, 15 g of carbohydrates, and 10 g of protein. Calculate the total energy content in $$\mathrm{kJ}.$$

Accepted Answer

$$20 	imes 39 + 15 	imes 17 + 10 	imes 18 = 780 + 255 + 180 = 1215\ \mathrm{kJ}$$

Question 13

Which of the following is a correct statement about the function of vitamin C in the human body?

Accepted Answer

Vitamin C is essential for the formation of connective tissue fibers and helps prevent wound failure and bleeding.

Question 14

A person is experiencing muscle weakness and partial paralysis. Which vitamin deficiency is most likely responsible, and what is the name of the disease?

Accepted Answer

Vitamin B1 (thiamine) deficiency; Beri-beri

Question 15

Which of the following best explains why lettuce has a much lower energy content compared to butter?

Accepted Answer

Lettuce is mainly composed of water, while butter is high in lipids, which provide more energy per gram.

Question 16

Which of the following is the correct sequence of events during the digestion and absorption of food?

Accepted Answer

Food is physically broken down, enzymes chemically digest macromolecules, and the resulting small molecules are absorbed through the gut wall.

Question 17

A nutritionist is comparing the energy content of two foods: 100 g of chocolate (energy content $$=2300\ \mathrm{kJ}) $$and 100 g of boiled potatoes (energy content $$=340\ \mathrm{kJ}). $$What is the most likely reason for the difference in energy content?

Accepted Answer

Chocolate contains more lipids and carbohydrates per gram than boiled potatoes.

Question 18

Which of the following best describes why vitamins are considered essential nutrients?

Accepted Answer

They are required in small amounts for normal physiological functions and cannot be synthesized in sufficient quantities by the body.

Vitamins, Food Energy, and Digestion: Study Notes for General Biology

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