Biology (Part-II) (UPSC)

Total Questions: 50

11. Consider the following statements. [1996]

AIDS-is transmitted

1. By sexual intercourse

2. By blood transfusion

3. By mosquitoes and other blood sucking insects

4. Across the placenta

Correct Answer: (b) 1, 2 and 4 are correct
Solution:AIDS is a viral disease. The virus is called HIV. This disease transmitted by sexual intercourse, blood transfusion and from pregnant mother to baby through placenta.
  • The word AIDS stands for Acquired Immuno Deficiency Syndrome. This means deficiency of immune system, acquired during the lifetime of an individual indicating that it is not a congenital disease [disease or abnormality present from birth]. ‘Syndrome’ means a group of symptoms.
  • AIDS was first reported in 1981 and in the last twenty-five years or so, it has spread all over the world

12. Which of the following would lead to malnutrition? [1996]

1. Overnutrition

2. Undernutrition

3. Imbalanced nutrition

Select the correct answer by using the codes given below Codes:

Correct Answer: (d) 1, 2 and 3
Solution:Malnutrition is defined as the insufficient, excessive or imbalanced consumption of nutrients. So under nutrition, over nutrition and imbalanced nutrition leads to malnutrition.
Causes of Malnutrition
  • Poverty: Limited access to nutritious food due to low income. For example, India had 160 million people in extreme poverty in 2023.
  • Economic and regional inequality: Lead to disparities in access to healthcare, education, and resources.
  • Food insecurity: Around 282 million people in 59 countries experienced high levels of acute hunger in 2023 (GRFC).
  • Lack of awareness: about nutrition, breastfeeding, and child care.
  • Poor sanitation: Increase the risk of infections, diseases and malnutrition as shown in the report ‘Improving Nutrition Outcomes with Better Water, Sanitation and Hygiene’ by UNICEF and WHO.
  • Gender inequality: Discrimination against women and girls. Children and women are at the forefront of hunger crises; over 36 million children under 5 years are acutely malnourished across 32 countries (GRFC).
  • Climate change: Impact agricultural productivity and food availability.

13. People drinking water from a shallow hand pump, are likely to suffer from all of the following diseases except : [1996]

Correct Answer: (d) Fluorosis
Solution:Cholera, Typhoid and Jaundice are water borne diseases. In shallow hand pumps there is possibility of microbial contamination (bacteria) to water. But fluorosis occurs due to excess amount of fluorine found in water.
  • Fluoride is an inorganic, monatomic anion of fluorine with the chemical formula F−1.
  • It is a common element that does not occur in the elemental state in nature because of its high reactivity.
  • It is considered a beneficial nutrient and is present in trace amounts in the body.
  • It is important for the integrity of bones and teeth. About 99% of the fluoride in the body is in the hard tissues.

14. Besides proteins and carbohydrates, other elements of nutritional value found in milk, include : [1996]

Correct Answer: (b) calcium and potassium
Solution:Besides proteins and carbohydrates, approximately 67% of calcium, 35% of magnesium and 44% of the phosphorus found in milk.

Milk is the liquid produced by the mammary glands of mammals, including humans. Breast milk is the preferred food for infants, as it is well-tolerated while their digestive tracts develop and mature. Dairy milk may be introduced at later ages if tolerated well. Although dairy milk may come from any mammal, cows, goats, buffalo, and sheep are common producers. This section will focus on dairy milk from cows, and briefly discuss non-dairy plant milk alternatives.
Whole cow’s milk contains about 87% water. The remaining 13% contains protein, fat, carbohydrates, vitamins, and minerals. Processing techniques remove fat to produce lower fat varieties: “reduced fat” contains 2% milkfat, “lowfat” contains 1% milkfat, and “nonfat” or “skim” has virtually no milkfat. Cows are often pregnant while they are milked, so dairy milk contains hormones like insulin-like growth factor-1 (IGF-1), estrogens, and progestins. Some cows are given additional hormones to increase milk production.

15. Fat present below the skin surface in our body, acts as a barrier against: [1996]

Correct Answer: (a) Loss of heat from the body
Solution:Fat present below the skin surface in our body, act as a insulator against loss of heat from the body. The deposited fat works as barrier, which prevents loss of heat.
  • Fat cells (adipocytes) contain lipids (fats) that don't conduct heat well, slowing its transfer out of the body.
  • The fat layer under the skin (subcutis) creates a substantial barrier, further reducing heat loss.
  • Adipose tissue also stores energy, and its insulating role helps conserve that energy by keeping the body warm.

16. The major chemical compound found in kidney stones is: [1996]

Correct Answer: (a) urea
Solution:

The composition of kidney stone is :
Calcium oxalate : 80%, Uric acid : 5%, Amino acid cystine : 2%, Magnesium and 13% ammonium phosphate.
In a nutshell, a kidney stone is a hard deposit which forms inside the kidneys. These stones often cause no permanent damage, but are known to cause significant pain. Depending on the type of material that forms the kidney stones, it can be classified into the following:
4 Types of Kidney Stones
Calcium Stones
Calcium stones, as the name implies, are made from calcium compounds. The most common among these is calcium oxalate. Such stones are usually caused when the body has high levels of calcium, usually as a result of certain medical conditions such as hyperparathyroidism.
Cystine Stones
One of the least common types of kidney stones are cystine stones. These stones are made of a compound called cystine and are common in individuals who have a condition known as cystinuria, where too much cystine is present in the urine.
Struvite Stones
Also called infection stones, struvite stones are made of struvite, a mineral produced by bacteria. These stones are usually composed of magnesium ammonium phosphate and are commonly formed in alkaline urine.
Uric Acid Stones
These stones, as the name implies, are made of uric acid. Uric acid is a waste product that is expelled from the body through urine. Some medical conditions, as well as certain lifestyle choices can increase the risk of these types of stones. These include a diet rich in red meat, increased alcohol consumption and diseases such as gout.

17. The pituitary gland by virtue of its tropic hormones controls the secretaoy activity of other endocrine glands. Which one of the following endocrine gland can function independent of the pituitary gland? [1997]

Correct Answer: (d) Parathyroid
Solution:Parathyroid gland is not controlled by pituitary. The parathormone which is secreted from this gland regulates calcium and phosphorus ion in body.
Parathyroid glands have one job: making and releasing parathyroid hormone (PTH). Together, PTH and another hormone — calcitonin — tightly control the levels of calcium in your bloodstream. Having too much or too little calcium in your blood can be associated with health issues. Calcium is one of the most important and common minerals in your body. About 99% of your body’s calcium is stored in your bones and teeth, while the other 1% of it circulates in your blood. Although it may be a small amount, the calcium in your blood is essential and helps:
  • Your nerves function properly.
  • Make your muscles squeeze together (contract) so you can move.
  • Your blood clot if you’re bleeding.
  • Your heart work properly.

18. Oxygen transportation in a human body takes place through : [1997]

1. Blood

2. Lungs

3. Tissue

The correct sequence of transportation is

Correct Answer: (c) 2, 1, 3
Solution:In human body oxygen first comes through lungs. From lungs to different tissue via blood.
Oxygen is essential for adenosine triphosphate (ATP) generation through oxidative phosphorylation; therefore, it must be reliably delivered to all metabolically active cells in the body. In the setting of hypoxia or low blood oxygen levels, irreversible tissue damage can rapidly occur. Hypoxia can result from an impaired oxygen-carrying capacity of the blood (eg, anemia), impaired unloading of oxygen from hemoglobin in target tissues (eg, carbon monoxide toxicity), or from a restriction of blood supply. Blood becomes typically saturated with oxygen after passing through the lungs, which have a vast surface area and a thin epithelial layer that allows for the rapid diffusion of gasses between blood and the environment. Oxygenated blood returns to the heart and is distributed throughout the body by way of the systemic vasculature.
Oxygen is carried in the blood in two forms. Most oxygen in the blood is bound to hemoglobin within red blood cells, while a small amount of oxygen is physically dissolved in the plasma. The regulation of unloading of oxygen from hemoglobin at target tissues is controlled by several factors, including oxygen concentration gradient, temperature, pH, and concentration of the compound 2,3-bisphosphoglycerate. The most critical measures of adequate oxygen transportation are hemoglobin concentration and oxygen saturation; the latter is often measured clinically using pulse oximetry. Understanding oxygen transport informs our understanding of the underlying mechanisms of tissue hypoxia, ischemia, cyanosis, and necrosis and management to improve global hypoxemia

19. Corpus luteum is a mass of cells found in : [1997]

Correct Answer: (b) Ovary
Solution:Corpus luteum is a mass of cells found in ovary. It produces progesterone hormone. If the ovary is not fertilised, the corpus-luteum degenerates after about two weeks and is gradually replaced by ordinary ovary tissue.

20. Alpha-keratin is a protein, present in: [1997]

Correct Answer: (b) Skin
Solution:Alpha keratin is a protein, found in skin, hair, nail, claws and hooves of animals.

Alpha Keratin is a coiled-coil. It is strong. inextensible, insoluble and chemically inert. Alpha Keratin is found in hair, wool, horn, and tails.