Sindh Botany 2019 — Solved MCQs

Question 1

Catkin inflorescence is observed in:

Accepted Answer

B. Mulberry — Mulberry (Morus spp.): Mulberries produce catkin inflorescence, which are long, cylindrical clusters of unisexual flowers. Male and female flowers are borne on separate catkins, with the male catkins being longer and more prominent. This type of inflorescence is characteristic of many members of the Moraceae family, including mulberries.

Question 2

Messenger RNA triplets are called:

Accepted Answer

B. Codon — This is the correct term. A codon is a sequence of three nucleotides on mRNA that corresponds to a specific amino acid or a stop signal during protein synthesis. It's the fundamental unit of the genetic code and is crucial for translating genetic information into proteins.

Question 3

Scientific study—of soil is called:

Accepted Answer

B. Pedology — Pedology specifically focuses on the scientific study of soils, including their formation, classification, and distribution. Pedologists examine soil properties, processes, and how they interact with the environment. It's the branch of soil science dedicated to understanding the characteristics and behavior of soils.

Question 4

Plants of intertidal zone of sea produce a jelly-like substance called:

Accepted Answer

B. agar — Agar is a gelatinous substance derived from seaweed and is commonly used in laboratories as a solidifying agent for microbiological media. It is indeed produced by some plants of the intertidal zone of the sea, particularly certain species of red algae.

Question 5

Multiple effect of a single gene is called:

Accepted Answer

A. PIeiotropy — Pleiotropy refers to the phenomenon where a single gene influences multiple, seemingly unrelated phenotypic traits. This means that a mutation in one gene can lead to various effects throughout the organism. For example, a gene responsible for coat color in animals might also affect other traits such as behavior or susceptibility to diseases.

Question 6

This biome is called the bread basket of the world:

Accepted Answer

D. Grassland — Grasslands, also known as prairies or steppes, are characterized by vast expanses of grasses and few trees. They are highly productive ecosystems for agriculture, with fertile soils and favorable climates for growing crops such as wheat, corn, and soybeans. Due to their high agricultural productivity and contribution to global food production, grasslands are often referred to as the "bread basket of the world."

Question 7

The attachment point of two chromatids of a chromosome is called:

Accepted Answer

D. Centromere — The centromere is the region of a chromosome where the two sister chromatids are joined together. It plays a crucial role in the separation of chromosomes during cell division

Question 8

At low temperature, ice crystals are formed in:

Accepted Answer

D. Cell Wall — At low temperatures, ice crystals can form within the extracellular space of plant cells, including the cell wall. These ice crystals can cause damage to the cell wall structure due to the expansion and contraction associated with the freezing and thawing process. This damage can lead to disruption of cell function and ultimately cell death.

Question 9

All are chemical messengers except:

Accepted Answer

D. ßiorhythms — Biological rhythms are cyclic physiological patterns of activities in an organism that are in response to periodic behaviour environmental changes.

Question 10

This hormone helps in the closing of stomata:

Accepted Answer

A. Abscisic acid — ABA is a plant hormone that plays a key role in regulating various physiological processes, including the closure of stomata. When plants experience water stress or drought conditions, the concentration of ABA increases, leading to the closure of stomata to reduce water loss through transpiration. Therefore, ABA helps in the closing of stomata.

Question 11

Crossing over takes place during this stage:

Accepted Answer

D. Diplotene — Exchange of chromatids parts takes place between paired chromosome due to breakage and rejoining of segments of chromatids as chiasmata . This is known as crossing over

Question 12

Only one of the following is a topographic factor of an ecosystem:

Accepted Answer

A. Earth surface — Topography refers to the physical features of the Earth's surface, including its elevation, slope, and relief. These features influence factors such as drainage patterns, soil formation, and microclimates, which in turn affect the distribution and abundance of organisms within an ecosystem. For example, mountain ranges can create barriers to the movement of species and influence precipitation patterns, while valleys may collect water and create unique habitats.

Question 13

The sea below 2000 meters having no light is called:

Accepted Answer

A. Abyssal zone — abyssal zone is the deepest region of the ocean, typically found at depths greater than 2,000 meters (6,562 feet). It is characterized by complete darkness, extremely high pressure, and low temperatures. Due to the lack of light penetration, photosynthesis cannot occur in this zone, and the biodiversity is relatively low compared to shallower zones.

Question 14

Exocytosis takes place if cell is placed in:

Accepted Answer

D. Hypertonic solution — In a hypertonic solution, the solute concentration outside the cell is higher than inside the cell. This causes water to move out of the cell via osmosis, leading to cell shrinkage. Exocytosis may still occur in a hypertonic solution, but the cell may be under stress due to the loss of water and subsequent shrinking.

Question 15

Plants, infected with disease, produce these chemical substances:

Accepted Answer

C. Phytoalexins — Phytoalexins are antimicrobial compounds synthesized by plants in response to infection by pathogens, such as bacteria, fungi, or viruses. They act as defense mechanisms to inhibit the growth of pathogens and protect the plant from disease. Phytoalexins are a crucial part of the plant's immune response.

Question 16

Indole acetic acid is the name of:

Accepted Answer

D. Auxin — ﻿Auxin is a plant hormone that regulates various aspects of plant growth and development, including cell elongation, apical dominance, and tropic responses. Indole acetic acid (IAA) is a naturally occurring auxin found in plants. It is involved in promoting cell elongation and differentiation, as well as root initiation. Therefore, indole acetic acid is a type of auxin.

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