One of the key organelles involved in digestion and waste removal is the lysosome. Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria.

Lysosomes are organelles inside animal cells that are fully membrane-bound; they're not present in red blood cells, though, and fungi have a similar structure called vacuoles that serves the same purpose but actually is not considered a lysosome.

Serous fluid originate from mixed glands, which contain both mucous and serous cells. A common trait of serous fluids is their role in assisting digestion, excretion, and respiration. In medical fields, especially cytopathology, serous fluid is a synonym for effusion fluids from various body cavities.

Aestivation or estivation refers to the positional arrangement of the parts of a flower within a flower bud before it has opened.

Vexilary aestivation is a mode of aestivation in which one large upper petal folds over, and covers, the other smaller petals, as in most papilionaceous plants.

C3 PLANTS

1. Examples of these plants are wheat, oats, bar¬ley, rice cotton, beans, spinach, sunflower, Chlorella etc..

2. Carbon pathway in photosynthesis is C3 pathway i.e. Calvin cycle only.

3. First stable product of above carbon pathway is 3-C compound phosphoglyceric acid (PGA).

4. The leaves have diffused mesophyll and only one type of chloroplasts.

5. Optimum temp, for photosynthesis is low to high.

6. Photorespiration occurs.

7. Photosynthetically less efficient.

8. Carbon dioxide compensation point is high, about 50 ppm.

9. Rate of C02 evolution in light is higher.

10. Carbonic anhydrase activity is higher.

11. Rate of translocation of end products of photosynthesis is low.

12. Optimum temperature for growth is low to high.

C4 PLANTS

1.Example of these plants are sugarcane, maize, sorghum, Atriplex, Amaranthus etc..

2.Carbon pathway in photosynthesis is C4—di- carboxylic acid pathway (Hatch-Slack path¬way).

3.First stable product of above carbon pathway is 4—C compound Oxaloacetic acid (OAA).

4.The leaves have ‘cane type’ of anatomy (Krantz anatomy) with compact mesophyll around the bundle sheath of vascular bundles and dimorphic chloroplasts. Those of bundle sheath are large and lack grana, while those of mesophyll are smaller and contain grana.

5.Optimum temperature for photosynthesis is high.

6.No photorespiration (or very little photorespiration).

7.Photosynthetically more efficient.

8.Carbon dioxide compensation point is low, 2 to 5 or even 0 ppm.

9.Rate of C02 evolution in light is apparently none.

10.Carbonic anhydrase activity is low.

11.Rate of translocation of end products of photosynthesis is high.

12.Optimum temperature for growth is high.

G2 phase, or Gap 2 phase, is the second subphase of Interphase in the cell cycle directly preceding mitosis. It follows the successful completion of S phase, during which the cell’s DNA is replicated.

G2 phase ends with the onset of prophase, the first phase of mitosis in which the cell’s chromatin condenses into chromosomes. G2 phase is a period of rapid cells growth and protein synthesis during which the cell prepares itself for mitosis

Exposure of mammalian cells to X rays results in prolongation of the cell cycle, including delays or arrests in G1, S and G2 phase. While G1-phase arrest occurs only in cells with wild-type p53 function, a G2-phase delay occurs in all cells regardless of p53 status. In this review, we summarize what is known about cell cycle progression through G2 and M phase and discuss the experimental findings that implicate different mechanisms in the G2-phase delay. Finally, we consider the possibility that G2-phase arrest plays a role in cell survival after irradiation.

Since each of the 20 amino acids is chemically distinct and each can, in principle, occur at any position in a protein chain, there are 20 × 20 × 20 × 20 = 160,000 different possible polypeptide chains four amino acids long, or 20n different possible polypeptide chains n amino acids long.

Twenty-two amino acids are naturally incorporated into polypeptides and are called proteinogenic or natural amino acids. Of these, 20 are encoded by the universal genetic code. The remaining 2, selenocysteine and pyrrolysine, are incorporated into proteins by unique synthetic mechanisms.

In earthworms regeneration of heads and tails commonly occurs when an injury activates stem cells that differentiate into replacement parts. The worm might grow a new head if cut behind the 13th segment. Another transformation occurs when tissue suddenly finds itself closer to the front or back of a regenerating worm. Through a process of cellular reorganization, the tissue conforms to its new role in the worm.An amputation between head and tail can sometimes result in two worms, with the front section growing a new tail and the severed tail growing a new head.