Biology

The retina is the sensitive layer of the eye that contains photoreceptor cells responsible for detecting light and sending visual signals to the brain. Other options like choroid, sclera, and cornea serve different functions but are not primarily sensitive layers.

Digestion of food is completed in the small intestine, where enzymes break down nutrients for absorption. The stomach initiates digestion, the large intestine absorbs water, and the liver produces bile but does not digest food directly.

At night, plants do not perform photosynthesis due to lack of sunlight, so they consume oxygen for respiration and release carbon dioxide as a byproduct. Therefore, they intake oxygen and release carbon dioxide at night.

Urine is produced in the kidneys, where blood is filtered to remove waste and excess substances, forming urine. The lungs, large intestine, and liver do not produce urine.

Valine is coded by four DNA codons: GTT, GTC, GTA, and GTG. Among the given options, only option A (GTT) is a valid DNA triplet that codes for valine. The other options code for different amino acids or are RNA codons.

Proteins are the chief builders of the body because they are essential for the growth, repair, and maintenance of body tissues. Carbohydrates and fats primarily provide energy, not structural building blocks.

If both parents are heterozygous carriers (heterogeneous normal) for a gene related to diabetes, the chance of their child inheriting the disease (assuming autosomal recessive inheritance) is 1/4, as the child must inherit two recessive alleles to express the condition.

Mitochondria are known as the powerhouses of the cell because they generate most of the cell's supply of ATP, used as a source of chemical energy.

Vitamin K plays a crucial role in blood clotting by aiding the synthesis of clotting factors in the liver. Vitamins B1, B2, and D do not have this function.

Individuals with blood group O are called universal donors because their red blood cells lack A and B antigens, allowing their blood to be safely transfused to people of any other blood group without causing an immune reaction.

The liver is the largest gland in the human body, responsible for numerous vital functions including detoxification, protein synthesis, and production of biochemicals necessary for digestion.

The primary function of feathers in birds is to provide insulation, helping to preserve body heat. While feathers also aid in flight and coloration, insulation is their fundamental role for survival.

Dialysis is a medical treatment used to remove waste products and excess fluid from the blood when the kidneys fail to function properly, making it a treatment for kidney failure.

Malaria primarily affects the spleen because the parasite infects red blood cells, leading to spleen enlargement and dysfunction as it filters infected cells from the blood.

The pituitary gland is known as the master gland because it controls the functions of many other endocrine glands by releasing various hormones.

A person with blood group AB is known as the universal recipient because they have both A and B antigens on their red blood cells and no anti-A or anti-B antibodies in their plasma, allowing them to receive blood from any group safely.

The tibia is one of the two long bones in the lower leg, commonly known as the shinbone. It is not found in the skull, arm, or face, making 'Leg' the correct answer.

A predator is an animal that captures and kills other living animals for food, which matches the definition given in the question. Parasites live on or in a host without killing it immediately, scavengers feed on dead animals, and mammals are a class of animals, not defined by feeding behavior.

Trachoma is a contagious bacterial infection that primarily affects the eyes, specifically the conjunctiva and cornea, leading to blindness if untreated.

The beautiful color patterns in a peacock's tail feathers arise due to interference of light caused by microscopic structures in the feathers, not selective absorption or reflection. This structural coloration results in iridescent colors.

The cerebrum is the largest part of the human brain, responsible for higher brain functions such as thought and action. The medulla oblongata and cerebellum are smaller parts involved in autonomic functions and coordination, respectively.

The medulla oblongata is a part of the human brainstem that controls vital autonomic functions such as breathing and heart rate. Therefore, it is correctly identified as part of the brain.

Leukemia is a type of cancer that affects the blood and bone marrow, characterized by the overproduction of abnormal white blood cells. Therefore, the correct answer is 'Blood'.

The normal body temperature of a healthy adult human is approximately 37.0 °C. Other options are either too high or too low to be physiologically normal.

The average resting heart rate for a normal adult male is typically around 70 beats per minute, which is within the normal range of 60 to 100 bpm.