Human Biology and General Science

An adult human skeleton typically contains 206 bones, which decrease from approximately 270 bones at birth due to fusion of separate bones during growth. The axial skeleton has 80 bones while the appendicular skeleton has 126 bones. Options A, B, and D are incorrect counts.

The pancreas secretes insulin from beta cells of the islets of Langerhans to regulate blood glucose levels. It also produces glucagon (from alpha cells) and digestive enzymes. Bile juice is produced by the liver, not the pancreas. Peptic juice refers to gastric secretions from the stomach.

The tibia (shinbone) is the larger and stronger of the two bones in the lower leg, connecting the knee to the ankle. It bears most of the body's weight. The fibula is the smaller leg bone. The skull contains cranial and facial bones, while arm bones include humerus, radius, and ulna.

The cerebrum is the largest part of the human brain, making up about 85% of brain weight. It is responsible for higher cognitive functions including thinking, memory, language, and sensory processing. The cerebellum coordinates movement, while the medulla oblongata controls vital autonomic functions like breathing and heart rate.

Calcium phosphate, specifically in the form of hydroxyapatite, is the primary mineral component of bones and teeth, providing hardness and strength. Bones are about 60-70% mineral (mainly calcium phosphate) and 30-40% organic matrix (collagen). Calcium carbonate is found in seashells, calcium sulfate in gypsum, and calcium nitrate is used in fertilizers.

Hemoglobin contains iron (Fe) in its heme groups, enabling it to bind and transport oxygen throughout the body. Each hemoglobin molecule has four iron atoms, allowing it to carry four oxygen molecules. Iron deficiency leads to anemia due to reduced oxygen-carrying capacity. Chlorine, calcium, and carbon are not structural components of hemoglobin.

The kidney's primary function is filtering blood and removing metabolic waste products like urea, creatinine, and excess salts through urine formation. While kidneys do help regulate blood pressure (via renin-angiotensin system), this is not their main function. Temperature regulation is managed by the skin and hypothalamus, and digestion involves the gastrointestinal tract.

Haemoglobin is a protein in red blood cells that binds to oxygen in the lungs and carries it to tissues throughout the body. Each haemoglobin molecule can carry up to four oxygen molecules.

Lachrymal glands, located above each eye, produce tears that lubricate and protect the eyes. Tears contain water, salts, and antibodies to keep eyes moist and clean.

The liver is the largest gland in the human body, weighing around 1.5 kg. It performs vital functions including detoxification, bile production, and nutrient metabolism.

The skin is the largest organ in the human body, covering approximately 2 square meters in adults. It provides protection, temperature regulation, and sensation.

People with blood group O (especially O negative) are called universal donors because their red blood cells lack A and B antigens, allowing transfusion to any blood type.

The pituitary gland is called the master gland because it produces hormones that regulate other endocrine glands. It controls growth, metabolism, and reproduction.

Newborns have approximately 300 bones, which fuse together during growth to form the 206 bones found in an adult human skeleton.

Vitamin A is essential for vision, maintaining healthy corneas and supporting the retina's function. It produces rhodopsin for low-light vision and prevents night blindness and xerophthalmia.

John B. Watson and behaviorist pioneers rejected introspectionist approaches, arguing psychology should study observable behavior instead. This paradigm shift dominated American psychology until the cognitive revolution of the 1950s-60s.

A complete circuit creates an uninterrupted path for electrons from the power source through the bulb and back, generating light. Without continuity like a break or missing component, the circuit remains open and no current flows.

The hypnagogic state occurs when drowsiness begins, producing sensory distortions, hypnagogic imagery, and dreamlike thoughts before true sleep. It precedes the hypnopompic state the transition from sleep to wakefulness.

Femto (f) is the SI prefix for 10^-15, between pico (10^-12) and atto (10^-18). Common uses include femtometers in nuclear physics for measuring atomic nuclei and femtoseconds in laser science.