General Science — Past Papers — Part 8 MCQs with Explanations

The air in Earth's atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen.

The rod cells of the retina are responsible for vision in dim light or at night (scotopic vision), Providing black and white, low-resolution vision, and contributing to peripheral vision. They are more numerous and more sensitive to light than cone cells, but they cannot detect color or fine details.

A device that opposes the flow of electrons in electronic circuits is called a resistor . It is a passive two-terminal component used to reduce current flow, divide voltage, and perform other functions by creating resistance. Resistance is measured in ohms (Omega).

Penguins are the birds which do not fly but swim to go from one place to another. Penguins have flippers which help them swim underwater. Penguin means پنکھ دار بحری پرندہ

Elephants, bears, chickens, monkeys, cows, wolf, birds, etc. are warm blooded animals Warm blooded means گرم خون والا

An invertebrate is an animal without a backbone. Worms, like earthworms, are classified as invertebrates. They lack a backbone and are found in various environments.

Venus and Mercury are the only planets in the solar system that do not have any natural satellites or moons. Likely due to their proximity to the Sun and gravitational influences.

The pressure of a gas in a container is affected by: Temperature (increases with temperature) Volume (decreases with increasing volume) Density of gas (increases with density) However, the material of the container does not directly affect the pressure of the gas.

During the daytime , plants require Carbon Dioxide (CO2) for photosynthesis. Which is the process by which they produce glucose and oxygen.

Distillation is a process that involves boiling the seawater and then collecting the condensed steam, which is free from salt and other impurities, resulting in fresh drinking water. This process is commonly used in desalination plants to produce drinking water from seawater.

Magnesium deficiency can contribute to or exacerbate all of the following health issues: Painful joints : Magnesium helps regulate inflammation and muscle function , and deficiency can lead to joint pain and stiffness. Osteoporosis : Magnesium is essential for bone mineralization and density; deficiency can increase the risk of osteoporosis and fractures. Memory loss : Magnesium plays a role in neuronal function and synaptic plasticity; deficiency has been linked to cognitive impairment and memory loss. Diabetes : Magnesium helps regulate insulin sensitivity and glucose metabolism; deficiency can increase the risk of developing type 2 diabetes.

Marasmus is a form of severe protein-energy malnutrition , characterized by a lack of sufficient protein and calories in the diet. It is most commonly seen in children under the age of 5 , particularly in developing countries where access to nutritious food is limited. Marasmus is caused by a severe deficiency of protein and calories, leading to : Wasting of muscles and tissues Weight loss Fatigue Weakness Poor growth and development

Herbivores are animals that eat only plants , including leaves, stems, roots, flowers, fruits, and seeds. Examples of herbivores include cows, deer, rabbits, and elephants.

Dust and gas in the interstellar medium (ISM) can absorb and scatter starlight. It leading to a reduction in the brightness of stars as seen from Earth. This is known as interstellar extinction.