Grade 11 Biology: Nutrition and Diet

Flashcards covering human nutrition, components of a balanced diet, macronutrients, micronutrients, deficiencies, and energy requirements based on Grade 11 Lesson 2.

What are the three main reasons the human body requires food?

1. Energy (cell respiration releases energy for movement, active transport, growth, and keeping warm)

2. Growth & Repair (materials for new cells, tissues, and replacement of damaged structures)

3. Health (vitamins, minerals, water, and fibre support normal body functions and help prevent deficiency)

What defines a balanced diet?

A balanced diet contains enough of every required component in proportions that match the body's needs.

What are the seven required components of a balanced diet?

Carbohydrate, protein, lipid, vitamins, minerals, water, and dietary fibre.

What is the primary biological function of carbohydrates in the human diet?

To provide glucose for cell respiration and energy release.

What are common food sources of carbohydrates?

Rice, bread, pasta, potatoes, oats, other cereals, and fruit.

What are the main functions of protein in the body?

Growth of new cells and tissues, repair of damaged tissues, and making proteins such as enzymes.

What are common sources of protein in the diet?

Meats, fish, eggs, dairy products, tofu, beans, peas, and nuts.

What are the key biological functions of lipids?

Long-term energy store, insulation beneath the skin, protection around organs, and forming part of cell structures.

How much energy in $kJ/g$ is released by complete oxidation of carbohydrates, proteins, and lipids?

Carbohydrate releases $17\,kJ/g$, protein releases $18\,kJ/g$, and lipid releases $39\,kJ/g$.

Which macronutrient in this chart releases over twice as much energy per gram as carbohydrate or protein?

Lipid, which releases $39\,kJ/g$ compared to $17\,kJ/g$ for carbohydrate and $18\,kJ/g$ for protein.

What is dietary fibre composed of, and what is its main function?

Dietary fibre is mainly indigestible plant material such as cellulose. It adds bulk, giving gut muscles something to push against to help prevent constipation.

What are four key functions of water in the body?

1. Solvent (many substances dissolve in it)
2. Transport (blood plasma carries dissolved substances)
3. Reactions (cell chemistry occurs in watery solutions)
4. Temperature control (sweating transfers heat away)

What is the biological function, source, and deficiency effect of Vitamin A?

Function: Needed to make a light-sensitive chemical in the retina and protect the surface of the eye. Sources: Carrots, liver, butter, margarine. Deficiency: Night blindness.

What deficiency condition caused by a lack of Vitamin A is pictured here?

Night blindness (difficulty seeing in dim light and slow adjustment to darkness).

What is the biological function, source, and deficiency effect of Vitamin C?

Function: Helps make connective tissue that binds cells together, supports healthy gums, and aids wound healing. Sources: Fresh fruit and vegetables. Deficiency: Scurvy (poor wound healing and bleeding gums).

What vitamin deficiency condition is shown by bleeding gums and poor wound healing in this image?

Scurvy, caused by a deficiency of Vitamin C.

What is the function of Vitamin D and what are its key sources?

Function: Helps growing bones absorb calcium and phosphate so they grow and harden. Sources: Oily fish, eggs, and skin exposure to sunlight.

What condition causing soft, bowed legs in children is shown in this image?

Rickets, caused by Vitamin D (or calcium) deficiency.

What is the biological function, source, and deficiency effect of Calcium?

Function: Needed to make and maintain teeth and bones. Sources: Dairy products, fish, bread, vegetables. Deficiency: Poor bone development and rickets.

What is the biological function of Iron and what condition results from its deficiency?

Function: Needed to make haemoglobin in red blood cells to carry oxygen. Deficiency: Anaemia, causing tiredness, low energy, and breathlessness after light activity.

What condition causing a swollen abdomen and ankles (oedema) due to severe protein deficiency is shown here?

Kwashiorkor, where low protein causes fluid to collect in tissues.

How do human energy requirements vary with activity levels, age, and pregnancy?

1. Activity level: More muscle activity increases respiration, so active people require more energy.
2. Age: Growth and changes in body size and activity patterns alter energy needs across life.
3. Pregnancy: Extra energy is needed for fetus and maternal tissue growth, plus elevated maternal metabolism.

If a food label states energy content as $1620\,kJ$ per $100\,g$, how much energy is in a $40\,g$ serving?

A $40\,g$ serving is $40\%$ ($0.40$) of $100\,g$, so: $0.40 \times 1620\,kJ = 648\,kJ$.

Why is the claim 'All fats are bad' a biological misconception?

Lipids are essential nutrients needed in appropriate amounts for long-term energy storage, insulation beneath the skin, organ protection, and cell structures.