Explanation: Mitochondria are double-membraned organelles found in almost all eukaryotic cells. They are known as the 'power house of the cell' because they generate adenosine triphosphate (ATP) through the process of cellular respiration. The inner membrane forms folds called cristae, which increase the surface area for enzyme activity related to energy production. Mitochondria also contain their own DNA and ribosomes, enabling them to produce some of their own proteins.

Key Reaction:

Glucose + Oxygen → Carbon dioxide + Water + ATP

The Itai-Itai disease is caused by Cadmium (Cd) poisoning. The disease was first identified in Japan, where industrial discharge of cadmium-contaminated water led to severe pollution. People consuming rice grown in this contaminated water suffered from extreme pain in bones and joints, along with kidney damage. The name "Itai-Itai" literally means "ouch-ouch" in Japanese, reflecting the severe pain experienced by victims.

Other options (for context)

• Nickel: Causes dermatitis and allergic reactions but not Itai-Itai disease.
• Chromium: Can cause skin and respiratory problems, not bone-related disorders.
• Mercury: Leads to Minamata disease, not Itai-Itai disease.

Explanation: According to the Bureau of Indian Standards (BIS) – IS 10500:2012, the acceptable limit of total hardness in drinking water, expressed as CaCO₃, is 200 mg/l. The permissible limit in the absence of an alternate source is up to 600 mg/l. Excess hardness can cause scaling and affect the taste of water.

Explanation: Carpal bones are the eight small bones that make up the wrist (also known as the carpus) in the human skeletal system. These bones are arranged in two rows — a proximal row (closer to the forearm) and a distal row (closer to the hand). They connect the bones of the forearm (radius and ulna) to the bones of the hand (metacarpals) and allow for the flexibility and movement of the wrist. The carpals are essential for various hand motions like bending, rotation, and gripping.

Explanation: Ecology is a branch of biology that deals with the relationships of living organisms with one another and with their physical surroundings. It examines how organisms adapt to their environment, how energy flows through ecosystems, and how matter cycles within the biosphere. The term “Ecology” was first coined by Ernst Haeckel in 1866.

Explanation: An alpha particle (α-particle) is a positively charged particle that consists of two protons and two neutrons, the same as the nucleus of a helium atom (He²⁺). It carries a +2 charge because of the two protons and has a mass number of 4. Alpha particles are emitted during the radioactive decay of heavy elements such as uranium, radium, and thorium. They have high ionizing power but low penetration ability and can be stopped by a sheet of paper or human skin.

Explanation: Bronchitis is an inflammation of the bronchial tubes, which are the air passages of the respiratory tract that carry air to and from the lungs. The condition causes coughing, mucus production, chest discomfort, and difficulty in breathing. It can be caused by viral or bacterial infections, long-term exposure to smoke, dust, or air pollutants. Chronic bronchitis is a serious form often associated with smoking and is part of a group of lung diseases known as COPD (Chronic Obstructive Pulmonary Disease).

Explanation: In GM food, the term GM stands for Genetically Modified. These are foods produced from organisms (plants or animals) whose genetic material (DNA) has been altered using modern biotechnology or genetic engineering techniques. This modification is done to introduce desirable traits such as pest resistance, drought tolerance, higher yield, or improved nutritional value. A common example is Bt cotton, which contains a gene from the bacterium Bacillus thuringiensis that provides resistance to insect pests.