The method of arranging organisms into groups oe sets on the basis of similarities and differences is called classification .

Importance  of classification

• It makes the study of wide variety of organism easy and in systematic manner .
• It helps to understand how the different organism have evolved with time.
• It helps to understand the inter-relationships among different groups of organisms.
• It forms a base for the study of other biological sciences , like biogeography

The size of lipids are much smaller compared to the other macro molecules.However lipids come under acid insoluble fraction.This is because in compounds lipids are present not only as such but also as structures like cell and other membranes..When we grind a tissue, cell membrane .etc will break and form vesicles which are not water soluble. Therefore this membrane fragments in the form of vesicles get separated along with acid insoluble pool.

Enzymes are soluble protein molecules that can speed up chemical reactions in cells. These reactions include respiration, photosynthesis and making new proteins. For this reason enzymes are sometimes called biological catalysts.

Enzymes speed up (catalyse) chemical reactions occurring inside and outside of living cells. This includes: DNA replication
Protein synthesis
Digestion

Enzymes react with substrates as part of the biological chemical processes that take place in human bodies, and their role in triggering these interactions is the basis of the descriptive term biological catalysts. Without the catalytic action of the enzymes, the products that human bodies require to produce energy do not form quickly enough.

Malonate is a competitive inhibitor of the enzyme succinate dehydrogenase: malonate binds to the active site of the enzyme without reacting, and so competes with succinate, the usual substrate of the enzyme. The observation that malonate is a competitive inhibitor of succinate dehydrogenase was used to deduce the structure of the active site in that enzyme.The chemical malonate decreases cellular respiration. It resembles the substrate succinate, without a -CH2-CH2 group required for dehydrogenation.

Zwitterions :Zwitterions(the word is derived from the German for "hybrid ion") are ions that are electrically neutral overall but contain nonadjacent regions of positive and negative charges; they are sometimes referred to as "dipolar ions." Examples of zwitterions are the free amino acids found in cells.

A blastopore is a hole that develops during the embryotic stages of development. It is a hole that enters the main gut of the animal and it either develops into the mouth or the **** depending on whether the organism is a protostome (mouth first) or deuterostome (mouth second). The embryotic state of an organism could be looked at and it could be determined if the organism were evolutionarily related to the protostomes or deuterostomes etc.

Blastopore:It is the opening by which the cavity of the gastrula, an embryonic stage in animal development, communicates with the exterior. During maturation of some animals it evolves into the mouth, in others it is covered over and contributes to the canal joining the primitive gut with the cavity of the neural tube, the primitive nervous system.

Blastopore: The opening of the archenteron in the gastrula that develops into the mouth in protostomes and the **** in deuterostomes.

Totipotent stem cells are one of the most important stem cells types because they have the potential to develop into any cell found in the human body.

A simple cell has the potential to develop into a specialized one with a specific job in the body. The zygote from that fusion of an egg cell and a sperm cell then begins cell divisions that are capable of forming the entire human body. It is these cells that are totipotent, so called because their potential is 'total.

Mitochondria and Chloroplast are two cell organelles .