Samacheer Class 9 Science - Nutrition and Health

• (a) Carbohydrates
• (b) Proteins
• (c) Vitamins
• (d) Fats

Answer:
(c) Vitamins

• (a) James Lind
• (b) Louis Pasteur
• (c) Charles Darwin
• (d) Isaac Newton

Answer:
(a) James Lind

• (a) Freezing
• (b) Irradiation
• (c) Salting
• (d) Canning

Answer:
(b) Irradiation

• (a) 1964
• (b) 1954
• (c) 1950
• (d) 1963

Answer:
(b) 1954

Answer: False. Correct Statement: Iodine is required for proper functioning of thyroid gland. Iron is essential for the formation of haemoglobin and oxygen transport in blood, but it is not the mineral required for thyroid function. Iodine is the specific mineral necessary for the synthesis of thyroid hormones, thyroxine and triiodothyronine, which regulate metabolism, growth, and development. Deficiency of iodine leads to goitre and hypothyroidism, whereas iron deficiency causes anaemia. Therefore, the statement that iron is required for thyroid function is incorrect.

Answer: False. Correct Statement: Vitamins are required in minute quantities. Although vitamins are essential nutrients necessary for various metabolic processes, growth, and disease prevention, they are needed only in very small amounts compared to macronutrients like carbohydrates, proteins, and fats. The body cannot synthesize most vitamins and must obtain them from food sources. Even though required in minute quantities, deficiency of any vitamin can lead to serious health problems and deficiency diseases. Therefore, the statement that vitamins are required in large quantities is incorrect.

Answer: True. Vitamin C is a water-soluble vitamin, meaning it dissolves in water and is not stored in the body's fatty tissues. Because of its water-soluble nature, excess vitamin C is excreted through urine, making it necessary to consume vitamin C regularly through diet. Water-soluble vitamins like vitamin C are easily absorbed in the small intestine and play crucial roles in immune function, collagen synthesis, and antioxidant protection. Sources of vitamin C include citrus fruits, tomatoes, and leafy vegetables.

Answer: True. Lack of fats in the diet may cause low body weight because fats are an important macronutrient that provides energy and supports various physiological functions. Fats are the most energy-dense macronutrient, providing nine calories per gram compared to four calories per gram for carbohydrates and proteins. Fats also aid in the absorption of fat-soluble vitamins such as vitamins A, D, E, and K, and are essential for maintaining healthy skin, hair, and hormonal balance. Insufficient fat intake can lead to inadequate calorie consumption, resulting in weight loss and malnutrition.

Assertion: Haemoglobin contains iron. Reason: Iron deficiency causes anaemia. Answer: (b) Both are true, but reason is not the correct explanation. Haemoglobin is a protein found in red blood cells that contains iron in its heme group, which enables it to bind and transport oxygen throughout the body. Iron is an essential component of haemoglobin's structure, and without iron, haemoglobin cannot be synthesized properly. While iron deficiency does indeed cause anaemia, this is not the correct explanation for why haemoglobin contains iron. Haemoglobin contains iron because iron is chemically necessary for the protein's oxygen-binding function, not because iron deficiency causes anaemia. The assertion and reason are both factually correct, but the reason does not logically explain the assertion.

Answer:

• Removes water by osmosis
• Prevents bacterial growth
• Reduces microbial activity

Used in:

• pickles
• fish
• meat
• canned foods

Answer: An adulterant is a substance that is added to food to increase its quantity, reduce its cost, or improve its appearance while lowering its quality, purity, or nutritional value. Adulterants are harmful substances that may be toxic or unsafe for human consumption. Common adulterants include addition of water to milk, mixing of inferior grains with superior ones, addition of artificial colors or flavors, and inclusion of non-food substances. Food adulteration is illegal and poses serious health risks to consumers. Regulatory agencies and quality control marks like AGMARK and ISI help prevent food adulteration and protect consumers.

Answer:

• Prussic acid in apple seeds
• Marine toxins in fishes

Answer: Vitamin D formation requires sunlight exposure. Sunlight exposure helps convert dehydrocholesterol, a precursor compound present in the skin, into vitamin D through a photochemical reaction. When ultraviolet B radiation from sunlight strikes the skin, it converts 7-dehydrocholesterol into previtamin D, which is then converted to active vitamin D through metabolic processes in the liver and kidneys. This is why vitamin D is often called the sunshine vitamin. Regular exposure to sunlight, typically fifteen to thirty minutes daily, is sufficient for adequate vitamin D synthesis in most individuals. Vitamin D is essential for calcium absorption, bone health, immune function, and overall health.

# (i) Drying

• Removes moisture
• Prevents microbial growth

Examples:

• grains
• fish
• dry fruits

# (ii) Smoking

Food exposed to smoke.

Examples:

• meat
• fish

Smoke preserves food by drying effect.

Answer:

May cause:

• diarrhoea
• nausea
• allergy
• asthma
• kidney damage
• liver disorders
• cancer

# FCI (Food Corporation of India)

Functions:

• Food grain distribution
• Buffer stock maintenance
• Farmer support
• Price regulation

# Quality Control Agencies

(a) Process

Pasteurization

(b) Dairy Product

Milk

(c) Temperature

followed by rapid cooling.

Answer: Leafy vegetables are recommended for anaemia because they contain iron, which is an essential mineral required for the formation of haemoglobin in red blood cells. Haemoglobin is the protein that carries oxygen throughout the body, and iron is a crucial component of its structure. Anaemia occurs when there is insufficient haemoglobin or red blood cells, often due to iron deficiency. Leafy vegetables such as spinach, fenugreek, and other green vegetables are rich sources of iron and other nutrients. Dates are also excellent sources of iron and other minerals. Consuming iron-rich foods helps increase iron levels in the blood, promoting the formation of new haemoglobin and red blood cells, thereby treating and preventing iron-deficiency anaemia.

Answer:

• Date of manufacture
• Expiry date
• FPO certification
• Ingredients
• Net weight

# In Agriculture

Biofertilizers

Examples:

• Rhizobium
• Azotobacter
• Nostoc

Biocontrol Agents

Example:

• *Bacillus thuringiensis* (Bt)

# In Industries

• Curd formation
• Fermentation
• Organic acid production
• Vitamin production

Immunization is crucial for developing resistance against infectious diseases by stimulating the immune system to produce antibodies and memory cells against specific pathogens. Vaccination protects children from serious infections by introducing weakened or inactivated forms of disease-causing organisms, enabling the body to recognize and fight these pathogens if exposed in the future. This prevents outbreaks of dangerous communicable diseases like measles, polio, diphtheria, and whooping cough, reducing morbidity and mortality rates in the population. Immunization also helps achieve herd immunity, where a large portion of the population is protected, preventing disease transmission to vulnerable individuals who cannot be vaccinated.

Assertion: Chickenpox causes scars. Reason: Rashes spread throughout body. Answer: (b) Both are true, but reason does not correctly explain assertion. Chickenpox scars are caused mainly when blisters are scratched or infected, not simply because rashes spread throughout the body. The formation of scars is a consequence of skin damage from secondary bacterial infection or mechanical trauma from scratching, rather than the mere presence of rashes across the body.

Assertion: Dengue can be treated by antibiotics. Reason: Antibiotics stop viruses. Answer: (d) Both false. Dengue is a viral infection caused by the dengue virus, and antibiotics are ineffective against viruses as they only target bacterial cell structures. Dengue treatment is supportive, focusing on managing symptoms like fever and pain, maintaining fluid balance, and monitoring for complications. Antibiotics cannot cure or treat viral diseases like dengue.

Answer:

• Maintain cleanliness and personal hygiene.
• Promote regular handwashing.
• Provide safe drinking water and proper sanitation.
• Ensure good ventilation in classrooms.
• Isolate and refer sick students when needed.
• Conduct vaccination and immunization programs where applicable.
• Control disease vectors such as mosquitoes.
• Conduct regular health checkups and health-awareness programs.