Explanation: Coriander (Coriandrum sativum) is a herb belonging to the family Apiaceae. The leaves are used as a fresh herb (commonly known as cilantro), and the dried fruits (often referred to as coriander seeds) are used as a spice. The fruits contain essential oils like linalool and borneol, which give coriander its characteristic aroma and flavor.

Uses:

• Leaves — used in cooking for flavoring and garnishing dishes.
• Dried fruits (seeds) — used as a spice, in curry powders, and for medicinal purposes (digestive aid).

Explanation: Below the critical temperature, gases can be liquefied by applying pressure because the intermolecular forces of attraction between gas molecules become effective. These forces pull the molecules closer together, resulting in the formation of a liquid state.

Explanation: The spectrophotometer measures bacterial growth by determining the optical density (OD) or turbidity of a culture. As bacteria multiply, the suspension becomes more turbid and absorbs more light. The absorbance value is proportional to the number of bacterial cells present.

Explanation: Diamond is the hardest natural form of carbon. In diamond, each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral structure, forming a strong three-dimensional lattice. This arrangement makes diamond extremely hard, dense, and transparent. It is used in cutting, drilling, and polishing tools. In contrast, graphite (another allotrope of carbon) is soft and slippery because its carbon atoms are arranged in layers with weak forces between them.

Explanation: The age of a tree is determined by counting the annual growth rings (also called annual rings) visible in a cross-section of its trunk. Each ring consists of a light band (spring wood) and a dark band (autumn wood), representing one year of growth. The study of these rings to determine a tree’s age and past climate conditions is known as dendrochronology.

Explanation: The disease AIDS (Acquired Immuno Deficiency Syndrome) is caused by the HIV (Human Immunodeficiency Virus). HIV attacks the body’s immune system, specifically the CD4 or T-helper cells, weakening the body’s ability to fight infections and diseases. It spreads through unprotected sexual contact, sharing of infected needles, transfusion of contaminated blood, or from an infected mother to her child during birth or breastfeeding. There is no permanent cure, but antiretroviral therapy (ART) helps control the virus and prolong life.

Explanation: Humans first develop a set of 20 milk teeth (also called deciduous or primary teeth) — 10 in the upper jaw and 10 in the lower jaw. These teeth start erupting around 6 months of age and are eventually replaced by 32 permanent teeth (including 4 wisdom teeth). Milk teeth help in early chewing, speaking, and maintaining space for permanent teeth.

Explanation: White Blood Cells (WBCs), also known as leukocytes, act as the body’s defense system. They protect the body against pathogens such as bacteria, viruses, and fungi. Different types of WBCs — like lymphocytes, monocytes, neutrophils, eosinophils, and basophils — have specialized roles in immunity. Because they “fight” infections, they are popularly called the ‘soldiers of the human body.’

Explanation: Carbon monoxide (CO) is a colorless, odorless, and highly poisonous gas. When inhaled, it competes with oxygen for binding sites on the haemoglobin molecule in red blood cells. CO has approximately 200–250 times greater affinity for haemoglobin than oxygen. As a result, it forms a stable compound called carboxyhaemoglobin (HbCO).

This compound prevents haemoglobin from carrying oxygen to body tissues, leading to oxygen deprivation (hypoxia). Prolonged exposure to CO can cause headache, dizziness, nausea, unconsciousness, and even death due to suffocation.

Chemical Reaction:

Hb + CO → HbCO (Carboxyhaemoglobin)