Tiêu đề Biology_IX_8_Review Questions.pdf ✅

ClassNotes UNDERSTANDING THE CONCEPTS Q#1 What are the effects of the lack of nitrate and magnesium ions on plant growth? Ans: Roles of Nitrogen: Plants get nitrogen in the form of nitrates. Nitrogen is a major component of proteins, hormones, chlorophyll, vitamins and enzymes essential for plant life. Nitrogen metabolism is a major factor in stem and leaf growth. Too much nitrogen can delay flowering and fruiting. Effects of the lack of nitrate ions: Deficiencies of nitrogen can reduce yields, cause yellowing of the leaves and stunt growth. Roles of Magnesium: Magnesium is a structural component of chlorophyll molecule and is necessary for functioning of plant enzymes to produce carbohydrates, sugars and fats. It is used for fruit and nut formation and essential for germination of seeds. Effects of the lack of magnesium ions: Deficiency of magnesium causes yellowing and wilting of leaves Q#2 How are the inorganic and organic fertilizers important in agriculture? Ans: Fertilizers: Nutrients applied to crops to speed up their growth is called fertilizers. Classification of Fertilizers: Fertilizers are broadly classified as organic or inorganic. a. Importance of inorganic fertilizers: Naturally occurring inorganic fertilizers, include rock phosphate, elemental sulfur, and gypsum that are not chemically modified. If nitrogen is the main element, they are often described as nitrogen fertilizers. Most inorganic fertilizers dissolve readily in water and are immediately available to plants for uptake. These fertilizers efficiently supply the required nutrients for plant growth www.classnotes.xyz Biology ClassNotes, Inc. © 2020 1
ClassNotes b. Importance of organic fertilizers: A natural organic fertilizer is the one that is derived from either plant or animal materials containing one or more essential elements. Organic fertilizers are more complex chemical substances that take time to be broken down into forms usable by plants. They have less salts so their larger amounts can be applied without injury to plant roots. However, their excessive amounts can cause environmental degradation due to nitrate leaching or run off of soluble organic compounds. Manure and compost are used as organic fertilizers. They can also increase soil drainage, aeration, water holding capacity, and the ability of the soil to hold nutrients. Q#3 Draw a table that can show the sources, energy values and functions of carbohydrates, proteins and fats. Ans: Carbohydrates Sources Energy values Functions Bread, pastas, beans, potatoes, bran, rice and cereals. Carbohydrates contain 04 kilocalories per gram. Carbohydrates are the basic source of energy for all animals. Proteins Meat, eggs, grains, legumes, and dairy products such as milk and cheese. One gram of proteins contains 04 kilocalories of energy. Proteins play an important role in the building of cellular protoplasm, muscles and connective tissues. Proteins are also required for making enzymes hormones and antibodies. Fats Milk, butter, cheese, eggs, One gram of lipids contains Lipids(fats) are used to form membranes, the sheaths www.classnotes.xyz Biology ClassNotes, Inc. © 2020 2
ClassNotes mutton, fish, mustard seeds, coconut, and dry fruits etc. 09 kilocalories of energy. surrounding neurons, and certain hormones. Lipids(fats) are also extremely useful energy sources. Q#4 How are vitamins A, C and D important in our diets? OR Describe the functions of vitamins A, C and D in our diets? Ans: Vitamins: Organic substances which are essential in small amount to regulate the metabolism and maintain the immune system are called vitamins. Importance of vitamin A/Function of vitamin A: Vitamin A was the first fat-soluble vitamin identified in 1913). It performs following functions. i. Vitamin A combines with a protein called opsin to form rhodopsin in the rod cells of the retina of eye. When vitamin A is inadequate, the lack of rhodopsin makes it difficult to see in dim light. ii. It is involved in normal cell differentiation, a process through which embryonic cells transform into mature cells with highly specific functions. iii. Vitamin A supports male and female reproductive processes and bone growth. iv. It is essential for immune function and vitamin-A deficiency causes decreased resistance to infections. iv. It is essential for immune function and vitamin-A deficiency causes decreased resistance to infections. Importance of vitamin C/Function of vitamin C (Ascorbic Acid): i. Vitamin C participates in many reactions by donating electrons, essential to the activity of many enzymes. Collagen: Vitamin C is needed to form collagen (a fibrous protein) that gives strength to connective tissues. Collagen is also needed for the healing of wounds. www.classnotes.xyz Biology ClassNotes, Inc. © 2020 3
ClassNotes ii. Vitamin C in white blood cells enables the immune system to function properly. Importance of vitamin D/Function of vitamin D: i. The best-known function of vitamin D is to help regulate blood levels of calcium and phosphorous ii. Vitamin D increases absorption of these minerals from the intestine and their deposition in bones. Q#5 Which foods contain calcium and iron and what role these minerals play in our bodies? Ans: Role of Calcium: 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. Foods Containing Calcium: Humans get calcium from milk, cheese, egg yolk, beans, nuts, cabbage etc. Effects of Deficiency of Calcium: 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. Role of Iron: Iron plays a major role in oxygen transport and storage and is a component of hemoglobin in red blood cells and myoglobin in muscle cells. Cellular energy production also requires iron which acts as enzyme cofactor. Iron also supports immune function. Foods Containing Iron: www.classnotes.xyz Biology ClassNotes, Inc. © 2020 4