Explanation

Explanation

Explanation

Bones do not secrete hormones, which are produced by glands in the endocrine system.

The parathyroid gland secretes parathyroid hormone.

It regulates calcium levels in the blood and bones.

Explanation

Explanation

COVID-19 primarily affects the lungs.

It leads to severe respiratory issues and pneumonia.

In critical cases, it can cause acute respiratory distress syndrome (ARDS), which can be lethal.

Explanation

Stomata are tiny pores (usually on leaves) that allow gas exchange (CO₂ in for photosynthesis, O₂ out).

They also regulate water vapor release (transpiration).

Explanation

Deserts have harsh conditions (extreme temperatures, low water), supporting fewer species.

This results in lower biodiversity compared to forests or grasslands.

Explanation

A food web is formed by interconnected food chains in an ecosystem.

It shows multiple feeding relationships and energy flow among organisms.

Explanation

Photosynthesis, the process of food synthesis in plants, primarily occurs in the leaves.

Leaves contain chlorophyll, which captures light energy to produce food from carbon dioxide and water.

Explanation

The recommended daily intake of Vitamin A for boys aged 13-15 years is around 5000 IU.

This helps in growth, vision, and immune function during adolescence.