Olympiad Test: Natural Resources- 3 - Class 9 MCQ

Hydrophytes are aquatic plants that live in water and are evolutionarily suited to thrive in aquatic environments. Hydrilla, also called water thyme is a submerged hydrophyte, which is a troublesome aquatic weed at many places.

In their natural habitats rats are primarily nocturnal—the brown rat is a prominent exception, being active day and night in both urban and rural environments. All rats are terrestrial, and many are also arboreal.

Horses have good vascularization, meaning there are lots of blood vessels going to large muscles. This allows for both explosive power and endurance power. All of these things combine to make horses run at a high speed.

To help them adapt to the ocean, whales developed echolocation, thick layers of blubber, modified lungs, better hearing, and larger arteries, among other things, to ensure their survival and prosperity.

The microbes which carry out biological nitrogen fixation are commonly called biological nitrogen fixers. for eg: Rhizobium and Azotobacter.

Oxygen, O₂

Ozone, O₃ is found upper layer of the atmosphere.