Explanation

• The nucleolus is a dense region inside the nucleus where ribosomal RNA (rRNA) is produced and ribosomal subunits are assembled.
• Ribosomes are responsible for protein synthesis in the cell.

Last verified on 27-10-2026

Explanation

• Tapetum is the innermost layer of the sporangium wall and provides nourishment to developing spores and pollen grains.
• It supplies nutrients and materials needed for the development of microspores.

Last verified on 27-10-2026

Explanation

• Thymine is a pyrimidine nitrogenous base found in DNA.
• But normally absent in RNA, where uracil takes its place.
• The two pyrimidine bases in RNA are uracil (U) and cytosine (C).
• Adenine (A) and guanine (G) are purine bases found in both DNA and RNA.
• DNA contains A, T, G, C.
• RNA contains A, U, G, C.

Last verified on 25-10-2026

Explanation

• Mitochondria produce most of the ATP (adenosine triphosphate) in eukaryotic cells through aerobic cellular respiration.
• ATP is the main energy-carrying molecule of the cell.
• It provides energy for various cellular activities.

Additional information:

• ATP is also produced in the cytoplasm during glycolysis.
• In plant cells, chloroplasts also produce ATP during photosynthesis.
• It is mainly for use within the chloroplast.

Last verified on 27-10-2026

Explanation

• Starlight passes through Earth’s atmosphere.
• Different air layers have different densities and temperatures.
• Light is repeatedly refracted (bent).
• This causes the star’s brightness to appear to change rapidly.
• This apparent change is called twinkling (scintillation).

Last verified on 26-10-2026