Grade 7 – Nutrition and Digestion Quiz

Which test is used to detect the presence of glucose in a food sample?

• Iodine Test

• Biuret Test

• Benedict’s Test

• Ethanol Test

Answer explanation

Benedict’s Test is specifically used to detect reducing sugars, including glucose, in food samples. The other tests mentioned are for starch (Iodine), proteins (Biuret), and lipids (Ethanol), making Benedict’s the correct choice.

Which organ is the primary site of nutrient absorption in the digestive system?

• Stomach

• Small Intestine

• Large Intestine

• Esophagus

Answer explanation

The small intestine is the primary site of nutrient absorption in the digestive system, where most digestion and absorption of nutrients occurs, unlike the stomach, large intestine, or esophagus.

Which test is commonly used to detect fats in a food sample?

• Biuret Test

• Iodine Test

• Ethanol Test

• Benedict’s Test

Answer explanation

The Ethanol Test is used to detect fats in food samples. When ethanol is added to a sample containing fats, a cloudy emulsion forms, indicating the presence of lipids. Other tests listed are for proteins or carbohydrates.

A positive result in Benedict’s test for glucose is indicated by a color change from blue to which of the following?

• Green, yellow, or brick red (depending on glucose concentration)

• Purple

• Orange

• No change

Answer explanation

A positive Benedict's test for glucose shows a color change from blue to green, yellow, or brick red, depending on the concentration of glucose present. Thus, the correct answer is the first option.

What is the main function of the stomach during digestion?

• Absorbing water

• Grinding food and mixing it with digestive juices

• Pumping blood

• Filtering toxins

Answer explanation

The main function of the stomach during digestion is grinding food and mixing it with digestive juices. This process helps break down food into smaller particles, making it easier for nutrients to be absorbed later in the digestive tract.

Which organ helps move food from the mouth to the stomach?

• Liver

• Esophagus

• Small Intestine

• Pancreas

Answer explanation

The esophagus is the organ that connects the mouth to the stomach, facilitating the movement of food through a series of muscular contractions known as peristalsis. The liver, small intestine, and pancreas have different functions.

Which food group is most important for building and repairing body tissues?

• Carbohydrates

• Proteins

• Fats

• Vitamins

Answer explanation

Proteins are essential for building and repairing body tissues, as they provide the necessary amino acids that serve as the building blocks for muscles, organs, and other tissues. Therefore, proteins are the most important food group for this function.

Which food group is mainly responsible for providing energy through carbohydrates?

• Fruits and Vegetables

• Grains and Cereals

• Proteins

• Dairy Products

Answer explanation

Grains and cereals are the primary food group that provides energy through carbohydrates, making them essential for fueling the body. Fruits and vegetables also contain carbs, but grains are the main source.

Which test is used to detect starch in a food sample?

• Benedict’s Test

• Iodine Test

• Biuret Test

• Sudan III Test

Answer explanation

The Iodine Test is specifically used to detect starch in food samples. When iodine is added to starch, it forms a blue-black complex, indicating the presence of starch, unlike the other tests listed.

When starch is present, the iodine test turns the sample what color?

• Red

• Blue-black

• Green

• Yellow

Answer explanation

The iodine test is used to detect starch. When starch is present, the iodine forms a complex with it, resulting in a blue-black color. Therefore, the correct answer is blue-black.