9th Class Biology Chapter 8 Notes English Medium
Important Notes of 9th Class Biology Chapter 8 Notes English Medium written by Honorable Sir Adnan Haider Suib. These notes are very helpful in the preparation of Nutrition Chapter 8 Class 9 for students of the 9th Class Biology Chapter 8 Notes English Medium these are according to the paper patterns of all Punjab boards.
Summary and Contents:
Topics which are discussed in the notes are given below:
- Very Important Multiple Choice Questions (MCQs) of Chapter No.8 Nutrition English Medium.
- CARBOHYDRATES: Carbohydrates are the basic source of energy for all animals. About half to 2/3 of the total calories
every animal consumes daily are from carbohydrates. Glucose is the most often used carbohydrate
for energy. Other useful carbohydrates are maltose, lactose, sucrose and starch. Carbohydrates
contain 04 kilocalories per gram. Humans get carbohydrates from the foods like bread, pastas,
beans, potatoes, bran, rice and cereals.
- Carbohydrates are the most common source of energy. Proteins and lipids are vital building
components for body but they can also be used for energy. Saturated fatty acids can increase a person’s cholesterol level. An increased cholesterol level
may eventually result in the clogging of arteries and, ultimately, heart disease.
- LIPIDS: The lipids present in food are composed of fatty acids bonded to glycerol. The fatty acids of lipids
may be saturated or unsaturated.
Saturated fatty acids have all of their carbon atoms bonded to hydrogen atoms.
- Unsaturated fatty acids have some of their carbon atoms double-bonded in place of a hydrogen
atom. Generally, the lipids containing saturated fatty acids are solid at room temperature. The lipids
containing unsaturated fatty acids are liquid at room temperature. For example butter contains
nearly 70% saturated and 30% unsaturated fatty acids. On the other hand, sunflower oil contains
nearly 75% unsaturated fatty acids. Lipids are used to form membranes, the sheaths surrounding
neurons, and certain hormones. Lipids are also extremely useful energy sources. One gram of
lipids contains 09 kilocalories of energy. Important sources of lipids include milk, butter, cheese,
eggs, mutton, fish,mustard seeds, coconut and dry fruits etc.
- PROTEINS: Proteins are composed of amino acids. Proteins are essential components of the cytoplasm,
membranes and organelles. They are also the major components of muscles, ligaments, and
tendons. So we use proteins for growth. Many proteins play role as enzymes. Proteins can also be
used for gaining energy. One gram of proteins contains 04 kilocalories of energy. Dietary sources
of proteins are meat, eggs, grains, legumes, and dairy products such as milk and cheese.
- MINERALS: Minerals are inorganic elements that originate in the Earth and cannot be made in body. They play
important roles in various body functions and are necessary to maintain health. Most of the minerals
in human diet come directly from plants and water, or indirectly from animal foods. Minerals are
categorized into major and trace minerals. Major minerals are required in the amounts of 100 mg
(milligrams) or more per day, while trace minerals are required in amounts less than 100 mg per
day. The roles of major and minor minerals in human body.
- Role of Calcium and Iron: Calcium is essential for the development and maintenance of bones and teeth. It is also needed
for maintaining cell membranes and connective tissues and for the activation of several enzymes.
Calcium also aids in blood clotting. Humans get calcium from milk, cheese, egg yolk, beans, nuts,
cabbage etc. Deficiency of calcium causes spontaneous discharge of nerve impulses which may
result in tetany, bones also become soft, blood clots slowly and wounds heal slowly.
- Iron plays a major role in oxygen transport and storage. It is a component of haemoglobin in red
blood cells and myoglobin in muscle cells. Cellular energy production also requires iron. It acts as
cofactor for many enzymes of cellular respiration. Iron also supports immune function. Humans
get iron from red meat, egg yolk, whole wheat, fish, spinach, mustard etc.