Answer:
characterized by presence or absence of antigens
the blood types are A, B, O, AB
Explanation:
There are two antigens and two antibodies that are mostly responsible for the ABO types. The specific combination of these four components determines an individual's type in most cases. Erythrocytes and serum were related to the presence of antigens on these erythrocytes and antibodies in the serum. these antigens are A and B, and depending upon which antigen the erythrocytes express, blood either belonged to blood group A or blood group B. A third blood group contained erythrocytes that reacted as if they lacked the properties of A and B, and this group was later called "O" blood group. The fourth blood group AB, was added to the ABO blood group system. These erythrocytes expressed both A and B antigens.
Blood group Antigen present on RBC Antibodies in serum Genotype(s)
A antigen A anti-B AA or AO
B antigen B anti-A BB or BO
AB both A and B antigen none AB
O none anti-A and anti-B OO
Answer:
False
Explanation:
In the troposphere, near the Earth's surface, human activities lead to ozone concentrations several times higher than the natural background level. Too much of this ground-level ozone is 'bad' as it is harmful to breathe and also damages vegetation.
The stratosphere or “good” ozone layer extends upward from about 6 to 30 miles and protects life on Earth from the sun's harmful ultraviolet (UV) rays.
When babies are born, their brains contain about a hundred billion of neurons. However, a few of these brain cells are connected. At age three, there are one thousand trillion connections formed. The brain starts to cut off unused connections at the age of eleven.
Answer:
- <u>Eukaryotes</u> are organisms that contain more than one cell with membrane-bound organelles and a nucleus.
- Organisms that contain only one cell and do not contain a nucleus or membrane-bound organelles are known as <u>prokaryotes</u>.
Explanation:
According to their structural and functional complexity, organisms can be classified into eukaryotes and prokaryotes.
- <em><u>Eukaryotic organisms</u></em><em> are formed by cells that have a true nucleus -where DNA is located- and specialized structures called organelles, with a system of endomembranes that compartmentalize the intracellular space. These organisms are usually pluricellular, given the ability of eukaryotic cells to group together to form tissues.
</em>
- <em><u>Prokaryotic organisms</u></em><em> are single cells, lacking a nucleus - genetic material is scattered in the cytoplasm - and do not possess organelles. The prokaryotic cells that form these organisms are incapable of binding together, so they do not form tissues.</em>
Some unicellular organisms are prokaryotic cells, like some parasitic microorganisms, such as amoebas.
