Explanation

• Species is the basic unit of classification.
• Species are a group of organisms that are morphologically similar and can interbreed.
• Classification system as proposed by Linnaeus.

These groups or levels are:

1. Kingdom
2. Phylum
3. Class
4. Order
5. Family
6. Genus 
7. Species

Species is the smallest unit of classification.

Last verified on 20-05-2026

Explanation

Thus, the First law of thermodynamics furnishes the relationship between:

• heat
• work
• the internal energy of the system

Explanation

Cement does typically contain a small percentage of gypsum.

Gypsum (calcium sulfate dihydrate, (CaSO4 ⋅ 2H2O) is added to cement primarily to regulate the setting time.

The percentage of gypsum in cement is usually around 2-5%.

It prevents the cement from setting too quickly by controlling the rate at which the cement hydrates and hardens. 

Explanation

The frequency of AC (Alternating Current) supply in Pakistan is typically 50 Hertz (Hz).

AC electricity alternates back and forth in a direction 50 times per second

Explanation

Thymine is the nitrogenous base which is not present in RNA

Thymine is one of the four nucleobases found in DNA (along with adenine, guanine, and cytosine)

Whereas RNA contains uracil (U) instead of thymine.

RNA uses uracil as a complementary base to adenine during transcription,

while DNA uses thymine as a complementary base to adenine during replication.

Explanation

The body is covered by a glandular epithelial envelope called a mantle

They secrete a calcareous shell

Explanation

Torricelli's theorem is specifically used to find the velocity of efflux.

It states that the velocity of fluid flowing out of an opening (such as a small hole in a container) can be found using the equation:

v=  under root 2gh

where:

 𝑣 is the velocity of efflux,

𝑔  is the acceleration due to gravity (approximately 9.81 m/s²),

ℎ  is the height of the fluid above the opening.

This theorem is particularly useful in situations involving the flow of liquids through openings or nozzles.

Explanation

For a diatomic gas (like O₂ or N₂), the ratio of specific heats 𝐶𝑝/𝐶𝑣 is approximately 1.4.

This ratio is also known as the adiabatic index (γ).

It is used in thermodynamic processes.

Explanation

According to the latest classification, Bryophyta is divided into three classes:

• Hepaticopsida (Liverworts)
• Anthocerotopsida (Hornworts)
• Bryopsida (Mosses)

Hepaticopsida (Liverworts):

The name Hepaticopsida comes from the word “hepatic” meaning liver.

Liverworts come under this class.

Hepaticopsida is further divided into 4 orders:

1. Marchantiales (e.g. Riccia, Marchantia)
2. Sphaerocarpales (e.g. Sphaerocarpos)
3. Calobryales (e.g. Calobryum)
4. Jungermanniales (e.g. Pellia)

Explanation

The use of transgenic farm animals to produce pharmaceuticals is commonly referred to as Gene pharming.

Gene pharming involves the genetic modification of farm animals to produce specific pharmaceutical products, such as:

• proteins or antibodies
• in their milk
• blood 
• other bodily fluids