Biology (Part-II) (UPSC)

Total Questions: 50

41. Lathyrism is caused by excessive consumption of : [1999]

Correct Answer: (a) khesari dal
Solution:Lathyrism is caused by excessive consumption of khesari dal. Lathyrism gets its name from scientific name of khesari dal which is Lathyrus sativus. The symptom of the disease is paralysis of both the lower limbs.
• In the late 19th century, an outbreak of lathyrism linked to grass pea led to its ban in India in 1961 under the Prevention of Food Adulteration Act.
• Despite the ban, grass pea cultivation continued, and researchers developed low-toxin varieties.
• In 2015, an expert committee recommended lifting the ban, emphasizing its potential for food security amid climate change.
• Lathyrism is a neurological disorder caused by eating too much grass pea (Lathyrus sativus).
• It’s also known as neurolathyrism.
• Lathyrism is one of the oldest known neurotoxic disorders.
• It’s a skeletal disorder caused by the toxin BAPN, which inhibits the copper-containing enzyme lysyl oxidase

42. Assertion (A): In human being, the females play a major role in determining the sex of the offspring. [2000]

Reason (R): Women have two 'X' chromosomes.

Correct Answer: (d) A is false but R is true
Solution:Assertion is false. In human, sex determination of offspring depends on male because male sperm contains XY chromosome, whereas female has XX chromosome in their ovum.
Sex Determination is the process that decides whether an organism develops as male or female. In most species, including humans, this depends on the combination of sex chromosomes inherited from the parents.
Humans typically have two sex chromosomes. Females carry two X chromosomes (XX), while males carry one X and one Y (XY). The Y chromosome contains crucial genes, such as the SRY gene, that trigger the development of male reproductive organs.
In some animals, however, genetics is not the only factor. Certain reptiles show temperature-dependent sex determination, where the incubation temperature of eggs decides whether the offspring will be male or female. Studying Sex Determination is important in genetics, medicine, and evolutionary biology, as it helps explain reproductive processes and the development of sexual traits across species.

43. At which stage in its life cycle, does the silk worm yield the fibre of commerce? [2000]

Correct Answer: (c) Pupa
Solution:Silk worm yield the fibre from pupa stage, which is commercially used to produce clothes.

Silk worm is not really a worm, but the larval form of the silk moth. The famous "silk" that the insect produces is spun to make their cocoons. Each cocoon may contain a single strand of silk one mile long.

44. Match List-I(Disease) with List-II (Types of disease) and select the correct answer using the codes given below: [2000]

List-I  List-II 
A. Haemophilia1. Deficiency disease
B. Diabetes2. Genetic disease
C. Rickets3. Hormonal disorder
D. Ringworm4. Fungal infection

Codes:

ABCD
(a)2341
(b)2314
(c)3214
(d)3241
Correct Answer: (b)
Solution:Haemophilia - Genetic disease caused in sex-linked gene. Diabetes-Hormonal disorder disease caused by imbalance of insulin hormone. Rickets - Nutritional deficiency disease caused by deficiency of vitamin-D. Ringworm-Caused by fungus.

45. The blood glucose level is commonly expressed as: [2000]

Correct Answer: (b) milligram per decilitre
Solution:The glucose level in blood is commonly expressed as milligram per decilitre.
• Unusually high or low blood glucose levels can potentially lead to acute and or chronic, life-threatening conditions.
• The value of blood sugar in humans generally ranges from 70 - 100 mg/dl. Blood sugar levels are regulated by the hormones insulin and glucagon which act antagonistically.
• These two hormones are secreted by the islet cells of the pancreas.
• When the blood glucose levels are high, insulin hormone is secreted which causes the liver to convert more glucose molecules into glycogen and when the blood glucose levels are low glucagon secreted act on liver cells to promote the breakdown of glycogen to glucose and increase the blood glucose concentrations.

46. Match List-1 (Endocrine glands) with List-II (Hormones secreted) and select the correct answer using the codes given below: [2000]

List-I  List-II 
A. Gonads1. Insulin
B. Pituitary2. Progesterone
C. Pancreas3. Growth hormones
D. Adrenal4. Cortisone

Codes:

ABCD
(a)3241
(b)2341
(c)2314
(d)3214
Correct Answer: (c)
Solution:Progesterone is secreted from gonads. Growth hormone is secreted from pituitary gland. Insulin hormone is secreted from pancreas. Cortisone is secreted from adrenal gland.

47. Thesensationoffatigue in the muscles after prolonged strenuous physical work is caused by : [2000]

Correct Answer: (d) the accumulation of lactic acid
Solution:Fatigue is caused by excess anaerobic metabolism, which results in production of excess lactic acid. This accumulated lactic acid causes the muscle pain.

Fatigue can be influenced by local muscle factors, the central nervous system, and general fitness.

48. A small pouch containing silica gel is often found in bottles of medicine in tablet or powder form because silica gel: [2000]

Correct Answer: (c) absorbs moisture
Solution:Silica gel granule is a network of inter-connecting microscopic pores, which attract and hold moisture by the phenomena known as absorption.
• Silica is another name for the chemical compound composed of two most abundant elements in Earth’s crust, silicon and oxygen, SiO2.
• The mass of Earth’s crust is 59 percent silica, the main constituent of more than 95 percent of the known rocks.
• Silica exists in many different forms that can be crystalline as well as non-crystalline (amorphous).
• Silica has three main crystalline varieties: quartz (by far the most abundant), tridymite, and cristobalite.

49. In the eye donation, which part of the eye is transplanted from the donor? [2001]

Correct Answer: (a) Cornea
Solution:During eye donation, only cornea is transplanted from donor to receiver. It is transparent front part of the eye and contains no blood supply.
The human eye is a sophisticated organ with various components working together to enable vision. Its main structures include:
Cornea: The transparent, dome-shaped outer layer that refracts and focuses light entering the eye.
Iris: The colored part of the eye containing muscles that regulate the size of the pupil to control the amount of light entering.
Pupil: The central opening in the iris that allows light to pass into the eye.
Lens: A flexible, transparent structure that adjusts its shape to focus light onto the retina for clear vision.
Retina: The light-sensitive layer at the back of the eye, containing photoreceptor cells (rods for dim light and cones for color vision) that convert light into electrical signals.
Optic Nerve: Transmits visual signals from the retina to the brain for interpretation.
Sclera: The white, tough outer covering that protects the eye and provides structure.
Aqueous and Vitreous Humors: Fluids maintaining eye shape and nourishing internal structures.
These components work in harmony to produce sharp, detailed, and colorful images.

50. A man whose blood group is not known meets with a serious accident and needs blood transfusion immediately. Which one of the blood groups mentioned below and readily available in the hospital will be safe for transfusion? [2001]

Correct Answer: (a) O, Rh
Solution:There is no A and B antigen on RBC of "O- "blood group, So O, Rh-is known as universal blood donor.
• Blood groups are classifications determined by the presence or absence of antigens on the surface of red blood cells and antibodies in the plasma.
• The most common system used is the ABO system, which categorizes blood into four groups: A, B, AB, and O. Blood type A has A antigens, B has B antigens, AB has both, and O has none.
• Another important factor is the Rh factor, which determines whether blood type is positive (Rh+) or negative (Rh−). For instance, a person can be A+ or O−.
• The compatibility of blood groups is crucial in blood transfusions, organ transplants, and pregnancy.
• Incompatible blood can cause serious immune reactions. For example, O− is considered a universal donor, while AB+ is a universal recipient.
• Understanding blood groups helps ensure safe medical practices and prevents complications in life-saving procedures.