Explanation

The state of inactivity in animals during summer or dry season is called aestivation (or estivation).

Purpose: To conserve energy and prevent water loss during arid, high-temperature conditions.

Duration: Lasts for the duration of the hot/dry season, ranging from weeks to months, or even years in some cases.

Explanation

• In the human heart, blood returning from the lungs via the pulmonary veins drains into the left atrium.
• From there, it flows through the mitral valve into the left ventricle, which pumps it out to the rest of the body through the aorta.

Explanation

Expansion of metal on heating is a physical change because it does not alter the metal’s chemical composition.

When cooled, the metal returns to its original size, showing that the change is reversible.

Explanation

Starfish belong to the phylum Echinodermata, which includes marine animals with radial symmetry and a water vascular system.

They have a tough, spiny skin and can regenerate lost arms, making them unique among marine organisms.

Explanation

Rhizopus is a genus of mold that belongs to the kingdom Fungi.

It is commonly found on bread, fruits, and decaying organic matter.

It reproduces through spores.

It is known for its role in food spoilage and some industrial applications.

Explanation

Oxygen is a byproduct of photosynthesis, not a required factor for the process.

Light, carbon dioxide, and chlorophyll are essential for photosynthesis to occur.

Explanation

Centrioles are present only in animal cells.

They are involved in cell division (spindle formation).

Higher plant cells typically lack centrioles and instead organize their spindle fibers differently.

Explanation

The critical angle for water (from water to air) is approximately 48.6°, rounded to 49°.

This is the angle of incidence above which total internal reflection occurs when light travels from water to air.

Explanation

The atomic mass of aluminum (Al) is 26.98, which is approximately 27.

This is the most common isotope of aluminum, which has an atomic number of 13.

Explanation

Acid rain reacts with minerals in stone structures, leading to their decay, which is termed "stone cancer."

It mainly affects limestone and marble, causing surface erosion and weakening of buildings and statues.