Q: The primary producer in an ecosystem are:

A: Bacteria

B: Women

C: Men

D: Plants



Correct Option: D  [ Plants ]

Remark:

Explanation: In any ecosystem, green plants (and some algae and cyanobacteria) act as primary producers. They convert solar energy into chemical energy through the process of photosynthesis, producing glucose and oxygen. This stored energy becomes the foundation of all food chains, supporting consumers and decomposers. Thus, plants form the first trophic level in an


Q: The HIV virus affects the:

A: Leucocytes

B: Lymphocytes

C: Erythrocytes

D: None of these



Correct Option: B  [ Lymphocytes ]

Remark:

Explanation: The HIV (Human Immunodeficiency Virus) primarily attacks the lymphocytes, especially the CD4⁺ T-helper cells of the immune system. This weakens the body’s defense mechanism, making it vulnerable to various infections and diseases, eventually leading to AIDS (Acquired Immunodeficiency Syndrome).


Q: The exit of food from the stomach is regulated by which muscle

A: cardiac

B: sphincter

C: skeletal

D: None of these



Correct Option: B  [ sphincter ]

Remark:

Explanation: The pyloric sphincter is a circular band of smooth muscle located at the junction of the stomach and the duodenum (first part of the small intestine). It regulates the passage of partially digested food (chyme) from the stomach into the small intestine and prevents backflow. The cardiac sphincter, by contrast, controls food entry into the stomach from the esophagus.


Q: What is the rarest blood type in the world ?

A: A

B: O positive

C: AB _

D: B



Correct Option: C  [ AB- ]

Remark:

Explanation: The rarest blood type in the world is AB⁻ (AB negative). It is found in less than 1% of the global population. People with AB⁻ blood can receive red blood cells from all Rh-negative blood types, but they can donate only to other AB individuals.


Q: Which of the following is the best conductor of heat ?

A: mercury

B: silver

C: leather

D: benzene



Correct Option: B  [ silver ]

Remark:

Silver is the best conductor of heat among the given options. It efficiently transfers heat due to the presence of free electrons that move easily within its metallic structure. Because of this property, silver is used in high-quality thermal equipment and electrical contacts.

  • Mercury: A metal but conducts heat less effectively than silver.
  • Leather and Benzene: Poor conductors of heat (insulators).


Q: The bats can fly in the dark because:

A: they can see the objects in darkness

B: they have weak legs and are likely to be attacked by predators

C: they generate flashes of light

D: they generate ultrasonic sound waves



Correct Option: D  [ they generate ultrasonic sound waves ]

Remark:


Q: Compound microscope has

A: two lenses

B: requires UV light source

C: used to view only dead organisms

D: requires large room space



Correct Option: A  [ two lenses ]

Remark:


Q: Which of the following is the uppermost layer of the atmosphere?

A: Stratosphere

B: Mesosphere

C: Ionosphere

D: Exosphere



Correct Option: D  [ Exosphere ]

Remark:

The Exosphere is the uppermost layer of the Earth's atmosphere. It lies above the thermosphere and gradually merges into outer space. The exosphere extends roughly from 700 km to 10,000 km above the Earth's surface. In this layer, air is extremely thin, and gas molecules such as hydrogen and helium are sparse and can even escape into space.

Other options (for context)

  • Stratosphere: Second layer from the Earth’s surface; contains the ozone layer.
  • Mesosphere: Lies above the stratosphere; meteors burn up here.
  • Ionosphere: A region within the thermosphere important for radio communication, not the outermost layer.


Q: Cuscuta is a :

A: Parasite

B: Saprophyte

C: Epiphyte

D: Xerophyte



Correct Option: A  [ Parasite ]

Remark:

Explanation: Cuscuta, commonly known as dodder plant or amarbel, is a total stem parasite. It lacks chlorophyll and cannot perform photosynthesis. Instead, it attaches itself to the host plant using specialized structures called haustoria that penetrate the host’s vascular tissues to absorb nutrients and water. Cuscuta is usually seen twining around host plants such as lucerne, hedg


Q: Which is an example of pollution-free energy?

A: Coal

B: Wind energy

C: Mineral oil

D: None of these



Correct Option: B  [ Wind energy ]

Remark:

Explanation: Wind energy is a clean and renewable source of energy that does not cause environmental pollution. It is generated by converting the kinetic energy of moving air into mechanical or electrical energy using wind turbines. Unlike fossil fuels such as coal or mineral oil, wind energy does not release carbon dioxide, sulfur dioxide, or other greenhouse gases. It is, therefore, a pollution-free and sustainable source of power, widely used for electricity generation in wind farms.
1...