Punjab Biology 2023 Paper 1 — Solved MCQs

Question 1

Which portion of nephron is under control of ADH?

Accepted Answer

C. Distal end and collecting duct — Antidiuretic hormone (ADH), also known as vasopressin, primarily acts on the distal convoluted tubule (DCT) and the collecting duct of the nephron in the kidneys. These segments of the nephron are responsible for regulating water reabsorption in the body. ADH increases the permeability of these segments to water, allowing more water to be reabsorbed back into the bloodstream, thus concentrating the urine and conserving water in the body.

Question 2

How many bones are involved in formation of each half of pelvic girdle?

Accepted Answer

A. 3 bones — Pelvic girdle attaches the hind limb to the vertebral column . It consists of two coxal bones. Each is formed by the fusion of three bones ilium, ischium and pubis.

Question 3

What do we call the cell surface membrane of a muscle fiber?

Accepted Answer

C. Sarcolemma — The cell surface membrane of a muscle fiber is called the sarcolemma. It surrounds the muscle fiber and plays a crucial role in muscle contraction and the transmission of signals between the nervous system and the muscle fiber.

Question 4

Effectors in human body which respond to stimulus are?

Accepted Answer

D. Glands and muscles — Effectors in the human body respond to stimuli. They include muscles, which contract or relax, and glands, which secrete substances in response to nervous or hormonal signals.

Question 5

B- cells of pancreas secrete hormone:

Accepted Answer

A. Insulin — B-cells of the pancreas secrete insulin, a hormone essential for regulating blood sugar levels by facilitating the uptake of glucose by cells. Insulin also plays a key role in promoting the storage of glucose as glycogen in the liver and muscles, thus helping to lower blood sugar levels after meals. Dysfunction of insulin secretion or action can lead to diabetes mellitus.

Question 6

Which disease is sexually transmitted?

Accepted Answer

B. AIDS — AIDS (Acquired Immunodeficiency Syndrome) is a sexually transmitted disease caused by the Human Immunodeficiency Virus (HIV). TB (Tuberculosis), on the other hand, is primarily transmitted through the air when an infected person coughs or sneezes, although it can also be transmitted through sexual contact in rare cases.

Question 7

Primary growth is due to to activity of

Accepted Answer

A. Apical meristem — Primary growth in plants, which involves the increase in length of the roots and shoots, is primarily due to the activity of apical meristems. Apical meristems are regions of actively dividing cells located at the tips of roots and shoots. These meristems produce new cells that elongate and differentiate, leading to the growth in length of the plant. The continuous activity of apical meristems allows for the primary growth of plants during development.

Question 8

rRNA in eukaryotes is synthesized by:

Accepted Answer

D. RNA polymerase III — RNA polymerase II (Pol II) catalyzes the synthesis of mRNAs and some specialized RNAs. RNA Polymerase III synthesizes tRNAs, the 5S rRNA, and some other small specialized RNAs.

Question 9

Start codon AUG represents the amino acid

Accepted Answer

C. Methionine — The start codon AUG represents the amino acid methionine (Met) in the genetic code. In addition to being the start codon, AUG can also code for methionine within a protein sequence, serving as both the initiation codon and an amino acid codon.

Question 10

During PCR how double helix is separated:

Accepted Answer

B. denaturation — During PCR (Polymerase Chain Reaction), DNA is separated through a process called denaturation. Denaturation is achieved by heating the DNA sample to a high temperature, typically around 94-98°C.

Question 11

The gene of blue opsins is present on

Accepted Answer

C. Autosome 7 — The gene for blue opsins is indeed located on autosome 7 in humans. This means that the specific autosome number for the gene encoding blue opsins is 7.

Question 12

In cystic fibrosis transmission of which is faulty resulting in disease?

Accepted Answer

D. Chloride — Cystic Fibrosis patients lack a gene that codes for trans-membrane carrier of the chloride ion.

Question 13

During PCR how DNA double helix is separated

Accepted Answer

A. By heat traetment — During PCR, the DNA double helix is separated primarily by heat, not enzymes. The denaturation step of PCR involves heating the DNA sample to a high temperature, typically around 94-98°C, which causes the hydrogen bonds between the two strands of the double helix to break. This results in the separation of the DNA into two single strands. Enzymes, such as DNA polymerase, are involved in other steps of PCR, such as primer annealing and DNA synthesis, but denaturation is primarily achieved through thermal cycling.

Question 14

Organs which are functionally similar but have different structures:

Accepted Answer

D. Analogous — Organs that are functionally similar but have different structures are known as analogous organs. An example of such organs are the wings of birds and the wings of insects. Both serve the function of flight, but they have evolved independently and have distinct structures.

Question 15

Bacteria and fungi are examples of:

Accepted Answer

C. Decomposers — Decomposers are organisms that break down dead organic matter, recycling nutrients back into the environment. Examples include bacteria, fungi, and certain insects, playing a crucial role in nutrient cycling within ecosystems.

Question 16

Zoological name of rhesus monkey is:

Accepted Answer

B. Macaca mulatto — The zoological name of the rhesus monkey is Macaca mulatta, belonging to the genus Macaca and species mulatta. Rhesus monkeys are commonly used in biomedical research due to their genetic and physiological similarities to humans. They are native to South, Central, and Southeast Asia, and are known for their distinctive red-brown fur and distinctive facial features.

Question 17

The decline in thickness of ozone layer is caused by increasing level of:

Accepted Answer

A. Chlorofluorocarbon — The decline in the thickness of the ozone layer is primarily caused by the increasing level of ozone-depleting substances (ODS), such as chlorofluorocarbons (CFCs), halons, and other similar compounds. These substances are human-made and release chlorine and bromine atoms when they reach the stratosphere. These reactive atoms then catalyze the breakdown of ozone molecules, leading to the depletion of the ozone layer.

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