Answer:
3,
Explanation:
Both purines and Pyrimidines are organic Nitrogen bases in DNA and RNA molecules. Adenine and Guanine are purines because they have double ring structure.Pyrimidine are three- cytosine,thymine and Uracil.The uracil is lacking in DNA,but present in RNA. furthermore thymine is only present ni DNA but not in RNA. However, cytocine is present in DNA and RNA. They are made up of single bonds.and are smaller than the Purines.
For perfect structure of DNA molecule,there must be complementary paring of Purines with corresponding pyrimidine. This paring ensures that for each purine (adenine) it must pair with corresponding(Thymine).While for each Guanine it must fit with corresponding Cytosine.(pyrimidine).
Two hydrogen bonds Hold A-T,while three hydrogen bonds hold G-T.
There above complementary paring is based on Chargaff’s Rule of compliment paring. Which states that the ratio of A-T and C-G will always constant in DNA molecule.That is the rates of these purines to pyrimidines will always be a fixed ratio.Thus each strand of DNA molecule will always complement one another for each A-T and C-G.
Answer: carbohydrate
Carbohydrates are sugars. They store short term energy and make up cell walls. Plants produce glucose, a carbohydrate, during photosynthesis to carry out the above functions. Other carbohydrates include lactose and starches, and they can be found in foods such as fruits, vegetables, bread, and pasta.
Answer:
A situation where your sympathetic nervous system would be active would be when you are running because your heart rate would increase.
Explanation:
Your sympathetic nervous system is in control of your heart rate, blood pressure, and blood vessels, so if you are running, your heart rate is speeding up, caused my this specific part of the nervous system.
An exocrine gland is a gland that secretes substances intended to be expelled from the body into the external environment, that is to say for example in the skin, the digestive tract or the respiratory tree. The exocrine glands deliver their secretion via an excretory duct. Some examples of the exocrine gland are salivary glands, sweat gland. mucous gland.
They are distinguished from endocrine glands that directly release their secretions into the bloodstream at the blood capillaries (still inside the body).
Some exocrine glands also have a role of endocrine gland, they are called amphicrine glands (like pancreas).
Atmosphere
biosphere
hydrosphere
the main oxygen cycle is photosenthisis
