Answer:
nitrogen fixation.
Explanation:
Nitrogen fixation is the process by which the combination of molecular nitrogen oxygen or hydrogen is given to give oxides or ammonium that can be incorporated into the biosphere. Molecular nitrogen, which is the majority component of the atmosphere, is inert and not directly usable by most living beings.
Answer: Two characteristics define brightness: luminosity and magnitude. ... The size of the star and its surface temperature determine its luminosity. Apparent magnitude of a star is its perceived brightness, factoring in size and distance, while absolute magnitude is its true brightness irrespective of its distance from earth.
Explanation:
The placenta is the interface between the maternal and embryo's blood, and allows for the exchange of nutrients, including oxygen and carbon dioxide exchange, but prevents certain drugs and chemicals from reaching the embryo. Its a bit like a security guard that only lets certain things though to the baby.
Answer:
c. DNA
Explanation:
The DNA is double stranded molecule that twist around each other to form a double helix structure. Each strand consists of nucleotide bases joined together by deoxyribose sugar-phosphate backbone.
<em>The two strands of the DNA lies anti-parallel to each other and each strand has two ends - the 5' end where the phosphate group gets attached to the 5′ carbon of a ribose sugar and the 3' end where there is a free hydroxyl group attached to the 3′ carbon of a ribose sugar.</em>
Hence, the correct option is c.
Answer:
Around 4.1 billion years ago, the first single celled life form appeared on Earth
