Explanation

Nucleic acids (DNA/RNA) are present in:

Nucleus:

• Contains genomic DNA (eukaryotic cells).

Mitochondria:

• Have their own mtDNA (vital for energy production).

Chloroplasts (in plants/algae):

• Contain cpDNA for photosynthesis-related functions.

Explanation

ATP (Adenosine Triphosphate) is called the energy currency of the cell because it stores and provides energy for cellular activities.

It releases energy when converted to ADP (Adenosine Diphosphate), which is then recycled back into ATP through cellular respiration.

Explanation

The increase in length (or volume) of solids when heated is specifically called thermal expansion.

Key Information:

Thermal Expansion:

• Occurs due to increased atomic vibrations with temperature.
• Linear expansion: Change in length (e.g., railroad tracks expanding in summer).
• Volumetric expansion: Change in 3D dimensions (e.g., mercury in thermometers).

Explanation

Cholesterol is a vital precursor in the biosynthesis of:

Vitamin D:

• Cholesterol converts to 7-dehydrocholesterol in the skin, which forms vitamin D₃ under UV light.

Steroid Hormones:

Cholesterol is the backbone for:

• Sex hormones (testosterone, estrogen, progesterone).
• Adrenal hormones (cortisol, aldosterone).

Explanation

Exponential notation (scientific notation) is used to express very small (e.g., 0.0000001) or very large (e.g., 1000000000) quantities compactly by representing numbers as powers of 10.

Key Information:

Format: a × 10^n, where 1 ≤ a < 10 and n is an integer.

Used for very large or very small numbers.

Examples:

• Large number: 6.022 × 10^23 (Avogadro's number)
• Small number: 1.6 × 10^-19 (Charge of an electron)

Explanation

• The Mole (mol) is the SI unit of amount of substance, representing 6.022 x 10^23 particles.
• It is used to measure the amount of a substance in a sample.

Explanation

Louis Pasteur (1822–1895) was a pioneering microbiologist and chemist whose work bridged both fields:

As a Chemist:

• Discovered molecular chirality (optical isomers).
• Studied fermentation, proving it was caused by microorganisms.

As a Microbiologist:

• Developed pasteurization (heat treatment to kill microbes in food).
• Created vaccines for rabies and anthrax.
• Disproved spontaneous generation (germ theory of disease).

Explanation

The chemical formula CH₃COOH represents acetic acid, a weak organic acid commonly found in vinegar.

Key Information:

Common Name: Acetic acid (systematic name: ethanoic acid).

Properties:

• Weak acid (partially dissociates in water).
• Pungent smell, sour taste (vinegar contains ~4–8% acetic acid).

Explanation

Xylem and Phloem are specialized conducting tissues in vascular plants:

Xylem: Transports water and minerals from roots to other parts (unidirectional).

Phloem: Transports sugars (photosynthates) from leaves to other parts (bidirectional).

Explanation

The atomic weight of Mercury (Hg) is 200.59 unified atomic mass units (u), as listed on the periodic table.

Key Information:

• Symbol: Hg (from Latin Hydrargyrum)
• Atomic Number: 80
• Standard Atomic Weight: 200.592 u (often rounded to 200.59 u).