DAT Question of the Day

Correct Answer: C. competitive inhibitor

If the particle can bind to the active site, it is competing for the active site with the substrate. A non-competitive inhibitor would bind to an allosteric site on the enzyme, causing a conformational change to the active site, preventing the substrate from binding. Positive and negative inhibitors are terms that do not exist in biology.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: C. Complete Dominance

Both of the brothers are phenotypically identical in regards to their hair texture. Genotypically, the two are different, as one is homozygous dominant and the other is heterozygous for hair texture. Despite the genotype differences the brothers are phenotypically similar with their hair texture because the dominant allele is the one being expressed. In both the case of Hh and HH, the presence of the dominant allele results in straight hair. This is due to complete dominance. In incomplete dominance, the heterozygote phenotypically is a hybrid between the two parents (i.e. a red and white flower make a pink flower). Whereas with codominance the heterozygote is phenotypically like both parents, i.e. red and white flower makes white plant with red spots. Law of independent assortment and law of segregation refer to Mendelian genetics, but are not the explanations for the phenotypic similarity between the two genotypes.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: C. Salt glands secrete the excess salt.

This is a great DAT comprehension question. Let’s run through the answer choices and see what we can eliminate. Choice [A] is wrong because there is no structure in the intestine that can physically eliminate salt. Choice [B] is wrong because most chordates have similar osmolarities. Choice [D] is incorrect because nephrons become longer to resorb MORE ions and water, not less. A classic example are rodents in the desert that have very long loops of Henle to resorb as much water and ions as possible. Lastly, specialized bacteria will still eliminate the salts after they’ve used them, so it does not solve the problem of excessive salt. Choice [C] is correct, sea birds have supraorbital glands, or salt glands, above their eyes, which secrete excess salt from their blood. It functions similar to a kidney, but is much more efficient at excreting salt.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: B. Transport proteins are often used by many substrates while channel proteins are generally used by ions.

Both of these types of proteins have a large variety in their shapes, sizes, and complexities. Therefore, no generalization can be made about them, and [C], [D], and [E] can be eliminated. Many transport proteins can use passive transport as well via uniport, for example, so [A] can be eliminated too. This leaves [B], where it states that channel proteins are used generally by ions. They aren’t called “ion channels” for nothing!

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.