Punjab Biology 2017 Paper 4 — Solved MCQs

Question 1

In urea cycle, the citrulline combines with ammonia to form:

Accepted Answer

A. Arginine — This is the correct answer. Arginine is formed when citrulline reacts with ammonia in the urea cycle. Arginine then undergoes further reactions to eventually produce urea, which is excreted by the body.

Question 2

The animals living in low supply of water, excrete their nitrogenous waste in the form of:

Accepted Answer

B. Urea — Urea is less toxic than ammonia and requires less water for excretion. Many mammals, including humans, excrete nitrogenous waste primarily in the form of urea. It requires less water for excretion compared to ammonia, making it suitable for animals in low water supply environments.

Question 3

Sea anemone has:

Accepted Answer

A. Hydro skeleton — Sea anemones have a hydrostatic skeleton, which is a structure supported by fluid pressure. They have a body wall comprised of two layers of cells, with a gelatinous layer in between. By controlling the movement of fluid within their body cavity, they can control their body shape and movement.

Question 4

Mature bone cells are called:

Accepted Answer

D. Osteocytes — Osteocytes are mature bone cells that are embedded within the bone matrix. They are derived from osteoblasts and are the most abundant cells in mature bone tissue. Osteocytes maintain the bone tissue by regulating mineral content and responding to mechanical stress.

Question 5

A growth retarding hormone is

Accepted Answer

B. Abscisic acid — ABA is a plant hormone involved in stress responses, seed dormancy, and stomatal regulation. It does not typically promote growth but rather regulates processes to conserve water and mitigate stress. It Inhibits stem and root growth notably during physiological stress, e.g. drought, and waterlogging.

Question 6

The hormone which develops the endometrium receptive for implantation of zygote is:

Accepted Answer

B. Progesterone — Progesterone is primarily responsible for preparing and maintaining the endometrium for implantation during the menstrual cycle. After ovulation occurs, progesterone levels rise, causing the endometrium to become more vascular and glandular, making it receptive to the implantation of a fertilized egg.

Question 7

Structure for the exchange of material is:

Accepted Answer

A. Placenta — This is an organ that develops in the uterus during pregnancy. It provides oxygen and nutrients to the growing fetus and removes waste products from the fetus' blood. The placenta also produces hormones that help maintain the pregnancy.

Question 8

From Henson's node dorsal mesoderm is formed and organized into:

Accepted Answer

B. Somites — Somites are blocks of mesoderm that form on either side of the neural tube in the developing vertebrate embryo. They give rise to various structures including the vertebrae, ribs, skeletal muscles, and dermis.

Question 9

Every gene starts with codon AUG which normally encodes the amino acid:

Accepted Answer

D. Methionine — Every gene starts with initiation codon AUG, which encodes the amino acid methionine.

Question 10

The phase of Mitosis, which ensures equal distribution of chromatids in daughter cells is:

Accepted Answer

C. Anaphase — Anaphase is the phase where sister chromatids are pulled apart toward opposite spindle poles. This separation ensures that each daughter cell receives an equal set of chromosomes.

Question 11

Microtubules are composed of a protein tubulin and traces of

Accepted Answer

A. RNA — These microtubules are composed of a protein tubulin and traces of RNA.

Question 12

The chance of an event to occur is called as

Accepted Answer

D. Probability — Probability is simply how likely something is to happen. Whenever we're unsure about the outcome of an event, we can talk about the probabilities of certain outcomes—how likely they are. The analysis of events governed by probability is called statistics.

Question 13

Cell supension cultures of cinchona ledgeriana produces

Accepted Answer

D. Quinine — Cell suspension cultures of Cinchona ledgeriana produce quinine.

Question 14

An essay on the principle of population was published by

Accepted Answer

C. Malthus — Essay on the Principle of Population. The first, published anonymously in 1798, was so successful that Malthus soon elaborated on it under his real name.

Question 15

Once nitrate enters the plant cell it is reduced to

Accepted Answer

B. Ammonium — Although plants can utilize ammonium directly, nitrate is the form in which most nitrogen moves from the soil into the roots. Once nitrate is within the plant cell, it is reduced back to ammonium.

Question 16

Northern coniferous forests are also called as

Accepted Answer

A. Taiga — Northern coniferous forests are also called Taiga. Conditions in taiga are harsher than those in the temperate deciduous forest. The winters are longer and colder, and the growing season is shorter.

Question 17

All non-cultivated plants and non-domesticated animals are called as

Accepted Answer

C. Wild life — All non domesticated and non cultivated biota in natural environment are called wild life.

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