Answer:
Sun.
Explanation:
The Sun and other gasses work together and increase the greenhouse gasses.
D. so the exchange of gases and nutrients can happen
A trilobite. Trilobites became extinct about 250 million years ago while a ammonite became extinct around the same time as dinosaurs(65 million years ago). You wouldn't find a human skull or a dinosaur footprint
Why study human genetics? One reason is simply an interest in better
understanding ourselves. As a branch of genetics, human genetics
concerns itself with what most of us consider to be the most interesting
species on earth: Homo sapiens. But our interest in human
genetics does not stop at the boundaries of the species, for what we
learn about human genetic variation and its sources and transmission
inevitably contributes to our understanding of genetics in general, just
as the study of variation in other species informs our understanding of
our own.
A second reason for studying human genetics is its
practical value for human welfare. In this sense, human genetics is more
an applied science than a fundamental science. One benefit of studying
human genetic variation is the discovery and description of the genetic
contribution to many human diseases. This is an increasingly powerful
motivation in light of our growing understanding of the contribution
that genes make to the development of diseases such as cancer, heart
disease, and diabetes. In fact, society has been willing in the past and
continues to be willing to pay significant amounts of money for
research in this area, primarily because of its perception that such
study has enormous potential to improve human health. This perception,
and its realization in the discoveries of the past 20 years, have led to
a marked increase in the number of people and organizations involved in
human genetics.
This second reason for studying human genetics is
related to the first. The desire to develop medical practices that can
alleviate the suffering associated with human disease has provided
strong support to basic research. Many basic biological phenomena have
been discovered and described during the course of investigations into
particular disease conditions. A classic example is the knowledge about
human sex chromosomes that was gained through the study of patients with
sex chromosome abnormalities. A more current example is our rapidly
increasing understanding of the mechanisms that regulate cell growth and
reproduction, understanding that we have gained primarily through a
study of genes that, when mutated, increase the risk of cancer.
Likewise,
the results of basic research inform and stimulate research into human
disease. For example, the development of recombinant DNA techniques (Figure 3)
rapidly transformed the study of human genetics, ultimately allowing
scientists to study the detailed structure and functions of individual
human genes, as well as to manipulate these genes in a variety of
previously unimaginable ways.
