Historically, african elephants have had large ivory tusks. for many years, poachers (illegal hunters) have been killing elephants that have large tusks so they could sell the ivory, which is valuable. now, many african elephants have small tusks or do not develop tusks. which of the following is true? . a.. the trait of tusk size in elephants has changed over time.. b.. poaching has had no effect on the size of elephant tusks.. c.. elephants without tusks are more likely to be hunted than elephants with large tusks.. d.. elephants without tusks cannot reproduce.

Rease is an enzyme used by plants to break down urea (a nitrogen-containing compound) into carbon dioxide and ammonia. urease urea > > > carbon dioxide and ammonia ammonia is broken down by plants into a nitrogen source plants need to grow. thus, plants could not use urea as a nitrogen source unless it was first converted to ammonia. in soybean plants there are two different kinds of urease, one produced in the seeds and the other produced in the leaves of the plant. three types of soybean plants were used in a set of experiments: normal soybeans and two mutant strains, one lacking the urease in the seeds only (strain 1) and one lacking urease in the leaves only (strain 2). experiment 1 separate areas in a field were planted with normal, strain 1, and strain 2 soybeans. all types of soybeans appeared to grow, flower, and produce seeds equally well. there were no externally detectable differences among the strains. experiment 2 small pieces of plant leaves of equal weight were obtained from each type of soybean plant and separately placed on media in culture dishes. tissue growing in this way will become an unorganized clump of cells referred to as callus. to provide a controlled nitrogen source, half the tissue samples of each type were placed on media containing urea, and the other half of the samples were placed on media containing ammonia. after 30 days, the weight gain for each of the callus samples was determined. results are shown in the table below.

How does human environment effect the biosphere

If t=tall and t=short what will be the physical appearance of the offspring the cross below? a. some will be tall and some will be short b. they will all be tall c. they will all be short d. they will be medium height