Biology – GK Questions

Ans: B

Explanation:The universal donor blood group is O negative (O-). This is because O- red blood cells do not have A, B, or Rh surface antigens, meaning they are unlikely to trigger an immune response in recipients of any blood type.
Correct_Option:B

Ans: C

Explanation:Decomposers, such as bacteria and fungi, play a crucial role in ecosystems by breaking down dead organic matter. This process returns essential nutrients back into the soil, making them available for producers (plants) to use. Therefore, they are vital for nutrient cycling and are not insignificant. They cannot produce their own energy (unlike producers) and do not act as primary producers. Option C accurately describes their function of recycling matter in the ecosystem.
Correct_Option:C

Ans: A

Explanation:TB (Tuberculosis) is a bacterial infection caused by Mycobacterium tuberculosis. Ascariasis is a parasitic worm infection. Chickenpox and the common cold are viral infections.
Correct_Option:A

Ans: A

Explanation:Lysosomes are membrane-bound organelles within a cell that contain digestive enzymes. They are often referred to as the “suicide bags” of the cell because they can break down and digest cellular waste, debris, and foreign invaders. In some cases, when a cell is damaged or stressed, the lysosomal membrane can rupture, releasing these enzymes and causing the cell to self-destruct through a process called autolysis.
Correct_Option:A

Ans: C

Explanation:Annelids, such as earthworms, have a closed circulatory system, not an open one. They possess a more complex nervous system with ganglia and nerve cords, not a simple nerve net found in cnidarians. Annelids are coelomates, meaning they have a true coelom, not a pseudocoelom found in pseudocoelomates. Gas exchange in many annelids occurs directly through their moist body surface (skin).
Correct_Option:C

Ans: A

Explanation:The adult human skull is composed of 22 bones. These are divided into cranial bones (8) and facial bones (14).
Correct_Option:A

Ans: A

Explanation:Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. Anatomy generally refers to the gross structure of organisms, while ecology studies the interactions between organisms and their environments. Taxonomy deals with the classification of organisms.
Correct_Option:A

Ans: D

Explanation:Mitosis is a process of cell division that results in two genetically identical daughter cells. During mitosis, chromosomes condense, the nuclear membrane breaks down, and spindle fibers form to separate the chromosomes. DNA replication, however, occurs during the S phase of interphase, which precedes mitosis.
Correct_Option:D

Ans: C

Explanation:Monocytes are the largest type of white blood cell (leukocyte) and play a crucial role in the immune system by differentiating into macrophages, which engulf pathogens and cellular debris. Lymphocytes, while important, are generally smaller. Basophils and neutrophils are also typically smaller than monocytes.
Correct_Option:C

Ans: C

Explanation:BOD stands for Biochemical Oxygen Demand. It is a measure of the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period.
Correct_Option:C

Ans: B

Explanation:Haemoglobin is a protein found in red blood cells that binds to oxygen and transports it throughout the body. It is responsible for the red color of blood. Insulin is a hormone that regulates blood sugar. Gastrin is a hormone that stimulates the production of gastric acid. Actin is a protein that forms part of the cytoskeleton and is involved in muscle contraction.
Correct_Option:B

Ans: A

Explanation:Allopatric species are those that inhabit different geographical areas, meaning they are geographically separated. This isolation can lead to the evolution of new species. Sympatric species, on the other hand, inhabit the same geographical area. Biospecies refers to a group of organisms that can interbreed and produce fertile offspring. Sibling species are morphologically similar but reproductively isolated species.
Correct_Option:A

Ans: D

Explanation:Viruses are microscopic infectious agents that are significantly smaller than bacteria. Their size typically ranges from approximately 20 nanometers (nm) to 300 nanometers (nm). While some viruses can be as small as 20 nm, others, like the Mimivirus, can reach up to 750 nm in diameter, but the general consensus for their typical range is up to 300 nm. Considering the provided options, 2 nm to 300 nm is the most encompassing and accurate range.
Correct_Option:D

Ans: B

Explanation:Both prokaryotic and eukaryotic cells share DNA as their genetic material. Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells possess both. The nucleus itself and the nuclear membrane are characteristic features of eukaryotic cells, not prokaryotic ones.
Correct_Option:B

Ans: B

Explanation:Pteridophytes, a group of vascular plants that includes ferns and horsetails, can have a very high number of chromosomes compared to humans, elephants, and bryophytes (mosses and liverworts). For example, some fern species have been reported to have over 1200 chromosomes. Humans typically have 46 chromosomes, and elephants have 56. Bryophytes generally have much lower chromosome numbers, often in the range of 10-40.
Correct_Option:B

Ans: C

Explanation:The human rib cage consists of 12 pairs of ribs, totaling 24 ribs. These are attached to the thoracic vertebrae in the back.
Correct_Option:C

Ans: A

Explanation:Xylem vessels are specialized plant tissues that are responsible for the transport of water and dissolved mineral salts from the roots to the rest of the plant, including the aerial parts. Phloem vessels, on the other hand, transport sugars produced during photosynthesis. Vascular bundles contain both xylem and phloem, but the specific conduction of water and minerals is primarily done by the xylem.
Correct_Option:A

Ans: A

Explanation:Homologous chromosomes are a pair of chromosomes in a diploid organism that have the same genes in the same order, one inherited from each parent. A tetrad refers to the structure formed by the pairing of two homologous chromosomes, each consisting of two sister chromatids, during meiosis. Gametes are haploid cells, a chromatid is one half of a replicated chromosome, and a zygote is a diploid cell formed by the fusion of two gametes. Therefore, a tetrad is the structure that directly represents the close association of homologous chromosome pairs during a critical stage of cell division.
Correct_Option:A

Ans: B

Explanation:The heart has three layers. The outermost layer is the epicardium, the middle layer is the myocardium, and the innermost layer is the endocardium. The pericardium is a sac that surrounds the heart.
Correct_Option:B

Ans: C

Explanation:Biotic pollutants are living organisms that contaminate water, such as bacteria, viruses, and algae. Non-biotic pollutants are non-living substances. Arsenic is a chemical element, a heavy metal, and therefore a non-biotic pollutant.
Correct_Option:C