Biology Questions

In flowering plants one sperm nucleus fertilizes the egg and the other sperm nucleus fuses with two other nuclei found within the ovule, thus forming triploid endosperm.

Hence, double fertilization is unique to flowering plants.

Capillaries Tiny blood vessels connecting arteries to veins. These blood vessels carry oxygen

and nutrients to individual cells. Capillaries are the smallest blood vessels in the body, and have

walls only one or two cells thick. (Their diameter is 5 to 10 micrometers, or 5 to 10 millionths of

a meter.)

Capillaries connect arterioles and venules, which are the smaller extensions of the larger arteries and veins.

The biogenetic law states that ontogeny (study of development) repeats phylogeny (origin from previous group of racial history), The young one of the frog namely the tadpole is like a fish cosidered to be ancestral to frog.

Nutrients are necessary for break down the food and supply energy to the organisms and to carry out essential life functions.

• Important nutrients are Hydrogen, Carbon and Oxygen.

• Some more important nutrients for plants are : Potassium, Sulphur, Nitrogen, Phosphorous, Calcium and Magnesium. 

The clotting of blood is a chain reaction initiated by the enzyme thrombokinase produced by the platelets. This causes prothrombin to be converted into thrombin in the presence of Ca++ion.

Thrombin combines with fibrinogen  to produce fibrin threads which entangles the corpuscles to form the clot.

If you were to produce a protein in bacterial cloning systems, you would not get the same post transcriptional and post translational modifications because the prokaryotic and eukaryotic systems work differently on the modifications.

Thus human recombinant protein genes are usually cloned in yeast cells. Also since they have a short generation time, they can be easily culture.