Ddt was harmful to birds because it prevented them from laying eggs.

True.

Explanation:

The statement is true.  

DTT or Dithiothreitol is a redox reagent used to stabilize proteins which possess free sulfhydryl groups. It is used to prevent intramolecular and intermolecular disulfide bonds from forming between cysteine residues of proteins.

DTT is was frequently used as a pesticide and it became very famous for its ability to kill all kinds of unwanted insects. However, species of birds were affected by this pesticide, such as bald eagles, peregrine falcons, and ospreys. The bird's calcium metabolism was altered in a way that resulted in a thin eggshells, due to the administration of DTT. The eggshells was not able to support the weight of the incubating bird.

This led to extinction of many bird species, because with no eggs being layed, then the bird population decreases.

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure

the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus