Through analysis of ice cores, scientists learn about glacial-interglacial cycles, changing atmospheric carbon dioxide levels, and climate stability over the last 10,000 years. Many ice cores have been drilled in Antarctica.
Very powerful microscopes were needed before cells could be observed in detail
A community refers to the total number of populations that inhabit a
specific location or area. This is part of the levels of organization of life. Arranged from the least complex to most
complex it falls 8th in the category. Below are the organization of life:<span>
a. Organelles - the basic part of a living
organism. It refers to the different structures of the cell, whether
prokaryotic or eukaryotic. (Ex. Mitochondria, nucleus)
b. Cells - building blocks of life that are
composed of different molecules responsible for the function of an organism.
(Example: prokaryotic, eukaryotic cells)
c. Tissues - combinations of cells that carry
out a specific function in an organism. (Example: Human skin)
d. Organs - collections of tissues that perform
specific functions. (Ex. heart, lungs)
e. Organ Systems - composed of interconnected
organs that function as a whole. Many organisms, particularly mamamals, are
composed of organ systems. (Ex. respiratory, circulatory systems)
f. Organisms – individual entities that
specifically make-up a population. (Ex. Each tree in the forest is an organism,
each animal in sea is an organism)</span>
g. Population – species living within a specific location. It could be
the same or different species that inhabit a place. (Ex. Birds are species in
the forest as well as bears)
h. Community – refers to the total number of populations that inhabit a
specific location. (Ex. All of the trees, insects, birds that inhabit the
forest are a community)
i. Ecosystem – consists of all living things that function together as a
group which also includes the non-living parts of the environment. (Ex. Rain
water, nitrogen in the soil)
<span>j. Biosphere – the highest organization of life that consist of all the
collection of ecosystems in the planet. It includes the land, air, water, even
the atmosphere of the planet. </span>
Answer:
a. heart development.
Explanation:
As the third week of fetal development starts, the process of formation of blood vessels begins. Also, the splanchnic mesoderm in the head end of the embryo forms heart on days 18 and 19. Since it develops heart, this part of the mesodermal cells is called the cardiogenic area. The underlying endoderm sends the induction signals to these mesodermal cells to form a pair of endocardial tubes that gradually develop into a single primitive heart tube.
This primitive heart begins to beat by the end of the third week of development. Therefore, any drug that affects fetal development during the first 20 days of the pregnancy might affect the development of the heart.
