Diet and Growth - Free MCQ Practice Test with solutions, Year 8 Science

Carbohydrates are the body's primary source of energy. They are broken down into glucose, which is utilized by cells to produce energy through respiration. This makes carbohydrates essential for sustaining energy levels during physical activities and daily functions.

Fats serve as a long-term energy store in the body. They are stored in adipose tissue and can be mobilized when the body requires energy, particularly during prolonged periods without food intake.

Regular exercise has been shown to improve mood and reduce feelings of anxiety and depression. Physical activity releases endorphins, which are chemicals in the brain that act as natural painkillers and mood elevators.

Fiber is essential for maintaining a healthy digestive system. It aids in regular bowel movements and prevents constipation by adding bulk to the stool, facilitating its passage through the intestines.

Ball-and-socket joints allow for a full range of motion in multiple directions, including circular movement. An example is the shoulder joint, where the rounded end of one bone fits into a cup-shaped socket of another bone.

A deficiency in Vitamin C leads to scurvy, which is characterized by symptoms such as weakness, swollen and bleeding gums, and skin problems. Historically, sailors on long voyages were particularly susceptible to scurvy due to a lack of fresh fruits and vegetables.

Proteins are crucial for building and repairing tissues in the body. They play a vital role in cell growth and maintenance, as well as the production of enzymes and hormones. This makes them essential for overall health and development.

Smoking causes damage to blood vessels, leading to their narrowing. This restricts blood flow and increases the risk of cardiovascular diseases, including heart disease. The harmful substances in tobacco smoke, such as nicotine and tar, contribute significantly to these effects.

Vitamin A is vital for healthy vision, particularly in low light conditions, and it supports the immune system by aiding the function of white blood cells. A deficiency in this vitamin can lead to night blindness and increased susceptibility to infections.

Calcium is critical for building and maintaining strong bones and teeth. It is a key mineral that makes up the structure of bones, and sufficient intake is essential to prevent conditions like osteoporosis later in life.

Vitamin A plays a vital role in supporting immune function and is crucial for maintaining healthy vision, especially in low-light conditions. It helps white blood cells fight infections and is essential for good eyesight. A deficiency in Vitamin A can lead to night blindness, illustrating its importance in visual health.

Iron is the key mineral required for the production of hemoglobin, which transports oxygen in the blood. A deficiency in iron can lead to anemia, characterized by fatigue and weakness due to insufficient oxygen delivery to tissues. Iron-rich foods include red meat, dark leafy greens, and legumes, emphasizing the need for a balanced diet to ensure adequate iron intake.

Carbohydrates are stored in the liver (and muscles) in the form of glycogen. This provides short-term energy that the body can use when needed, especially between meals or during physical activity.

Excessive sugar consumption is a major contributor to tooth decay. Sugars feed harmful bacteria in the mouth, which produce acids that erode tooth enamel, leading to cavities. Maintaining good oral hygiene and limiting sugar intake are essential for dental health. Interestingly, it is recommended to consume sweets in moderation and to combine them with other foods to minimize their impact on teeth.

Cereal grains are rich in dietary fiber (mainly cellulose). Fiber is important for maintaining digestive health, preventing constipation, and facilitating smooth passage of food through the intestines. Fruits, vegetables, and seeds are also good sources.