Biology- 1 - SSC CGL Free MCQ Test with solutions

Mitosis produces two daughter cells with identical genetic content, used for growth and repair in somatic cells. Meiosis, however, occurs in reproductive cells, producing four non-identical haploid cells for sexual reproduction. Statement ii is incorrect as meiosis does not occur in somatic cells and does not produce identical cells.

Mitochondria are known as the powerhouse of the cell, producing energy through ATP synthesis during cellular respiration. The nucleus controls cell activities, the Golgi apparatus modifies and packages proteins, and the endoplasmic reticulum is involved in protein and lipid synthesis.

Photosynthesis occurs in chloroplasts, which contain chlorophyll, the pigment that captures light energy to convert carbon dioxide and water into glucose and oxygen. Other organelles like the nucleus, mitochondria, and vacuole have different functions.

Sickle cell anemia is caused by a mutation in the HBB gene, leading to abnormal hemoglobin and sickle-shaped red blood cells. Down syndrome and Turner syndrome are chromosomal disorders, while cystic fibrosis is caused by mutations in the CFTR gene.

Alveoli are tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged with the blood. The trachea conducts air, the diaphragm aids breathing by contracting, and bronchioles distribute air but do not produce mucus.

The pituitary gland secretes growth hormone (GH), which regulates growth and metabolism. Insulin is produced by the pancreas, adrenaline by the adrenal glands, and thyroxine by the thyroid gland.

The equation represents photosynthesis, where plants use carbon dioxide, water, and light energy to produce glucose and oxygen. Respiration is the reverse process, transpiration involves water loss, and fermentation produces energy without oxygen.

An ecosystem consists of biotic factors (living organisms), abiotic factors (non-living components like air and water), and trophic levels (energy transfer levels). Fossil fuels are not a component of an ecosystem but a resource.

Mendel’s law of segregation is correct, stating that alleles segregate during gamete formation. However, DNA replication occurs during the S phase, not the G2 phase, making statement ii incorrect.

Sexual reproduction involves the fusion of male and female gametes to form a zygote. Binary fission, budding, and vegetative propagation are forms of asexual reproduction.

The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine. The liver, heart, and pancreas have different functional units and roles.

Nitrogen fixation by bacteria like Rhizobium converts atmospheric nitrogen into compounds plants can use, benefiting agriculture. Tuberculosis, food spoilage, and dengue are harmful effects of microorganisms.

Auxins promote cell elongation and growth in plants. Cytokinins stimulate cell division, gibberellins promote stem elongation, and abscisic acid regulates stress responses.

Gonorrhea is a bacterial STD. Tuberculosis, malaria, and dengue are not sexually transmitted; they are caused by bacteria, parasites, and viruses, respectively, and spread through other means.

Charles Darwin proposed the theory of natural selection, explaining how species evolve through differential survival and reproduction. Mendel studied heredity, Pasteur worked on microbiology, and Crick co-discovered DNA structure.

Red blood cells contain hemoglobin, which binds oxygen for transport. The pulmonary artery carries deoxygenated blood to the lungs, the aorta carries oxygenated blood to the body, and platelets aid in clotting.

Project Tiger is a conservation program launched in 1973 to protect tigers in India. Project Elephant focuses on elephants, Operation Blue Star was a military operation, and Green India Mission addresses afforestation.

Bt crops, genetically modified to produce a toxin against pests, are a biotechnological application. Deforestation, fossil fuel extraction, and plastic pollution are environmental issues, not biotech applications.

The carbon cycle balances carbon in the biosphere, and photosynthesis (carbon fixation) and respiration (carbon release) are key processes driving this cycle, making R the correct explanation of A.

The retina contains photoreceptors that detect light and convert it into electrical signals sent to the brain. The cornea and lens focus light, and the iris controls light entry.