Answer:
O Community
Explanation:
A community is made up of many populations within a specific area a certain period of time.
- A population is group of organisms of the same species that can interbreed and produce viable offspring
- Populations of organisms in a specific area or region is known as a community.
- An example is a community made up birds population, human beings, lizards etc.
The ozone layer is supposed to block ultraviolet rays.
Answer:
True
Explanation:
Adenine and Guanine fall under the category of Purine nitrogenous base. Purine is made of six member pyrimidine ring fused to five member imidazole ring. It is water soluble in nature.
A purine always pairs with a pyrimidine base to form a DNA base pair. Thymine and Cytosine are the two pyrimidine bases. Adenine bonds with Thymine by forming two hydrogen bonds and Guanine is bonded to Cytosine via three hydrogen bonds. When a purine base is formed it self inhibits formation of more purine and also activates formation of pyrimidine base. Hence, amount of purine and pyrimidine are almost equal in cell.
Answer:
To move substances against a concentration or electrochemical gradient, a cell must use energy. Active transport mechanisms do just this, expending energy (often in the form of ATP) to maintain the right concentrations of ions and molecules in living cells.
Explanation: