<span>As the pollen tube penetrates the ovule, it releases two sperm cells. As in gymnosperms, the ovule becomes a seed, encasing the embryo and endosperm in a seed coat. But unlike gymnosperms, in angiosperms the ovary containing the ovules develops into a fruit after fertilization.</span>
Bio accumulation of DDT lead to bird eggs with weak shells and non viable offspring. The lethal effects of DDT on birds was first noted in 1950; scientists discovered that earthworm was accumulating the DDT pesticide and that the robins that were preying on the earthworms were been poisoned. Further research revealed that the chemical cause thinning of the egg shell and production of non viable offspring. The chemical has since been banned in USA.
Answer:
The large intestine eliminates solid wastes that remain after the digestion of food. The liver breaks down excess amino acids and toxins in the blood.
Explanation:
Griffith's experiment worked with two types of pneumococcal bacteria (a rough type and a smooth type) and identified that a "transforming principle" could transform them from one type to another.
At first, bacteriologists suspected the transforming factor was a protein. The "transforming principle" could be precipitated with alcohol, which showed that it was not a carbohydrate. But Avery and McCarty observed that proteases (enzymes that degrade proteins) did not destroy the transforming principle. Neither did lipases (enzymes that digest lipids). Later they found that the transforming substance was made of nucleic acids but ribonuclease (which digests RNA) did not inactivate the substance. By this method, they were able to obtain small amounts of highly purified transforming principle, which they could then analyze through other tests to determine its identity, which corresponded to DNA.
