Explanation

Photosynthesis involves:

• Energy-Rich Carbohydrates are Synthesized: Photosynthesis is the process by which plants convert light energy into chemical energy, primarily in the form of glucose (a carbohydrate) and other sugars.
• CO₂ and H₂ of Water are Reactants: During photosynthesis, plants take in carbon dioxide (CO₂) from the atmosphere and water (H₂O) from the soil.
• The hydrogen from the water molecule is used in the synthesis of glucose.
• Chlorophyll Alone Converts Light Energy to Chemical Energy: Chlorophyll, the green pigment in plants, plays a crucial role in capturing light energy.
• This light energy is then converted into chemical energy, which powers the synthesis of glucose.

Explanation

AIDS is caused by HIV.

It spreads through infected needles, sexual contact, and unsafe practices.

It is not transmitted by casual contact like touching or sharing food.

Explanation

Aquatic arthropods like crabs, prawns, and some aquatic insects use gills to extract oxygen from water.

Gills provide a large surface area for gas exchange in an aquatic environment.

Explanation

Geotropism is the growth response of plants toward or away from gravity.

Roots show positive geotropism (grow downward) and shoots show negative geotropism (grow upward).

Explanation

The Metric System of Measurements uses the mass units: gram (g), kilogram (kg), and tonne (t). 1000 g = 1 kg. 1000 kg = 1 tonne.

Mass was first defined in 1795

Symbol: M

Explanation

A central force always acts along the line joining the object and a fixed point (the center).

Gravitational and centripetal forces are specific examples of central force.

Explanation

The book is at rest with no net force or motion, so it is in static equilibrium.

Since any small push won’t topple it, it is also considered stable equilibrium on a flat surface.

Explanation

Urea is the most widely used nitrogenous fertilizer in Pakistan due to its high nitrogen content (46%).

It is cheap, effective, and easily available compared to other nitrogen fertilizers.

Explanation

Neon is a noble gas that exists as single atoms (mono-atomic) in nature.

Oxygen (O₂), Nitrogen (N₂), and Fluorine (F₂) are diatomic molecules.

Explanation

DAP (Diammonium Phosphate) is a synthetic chemical fertilizer rich in nitrogen and phosphorus.

Manures and compost are natural fertilizers, not synthetic.