Question 1: The right answer is D.
Living organisms contain four basic elements: Oxygen, Nitrogen, Carbon, and Hydrogen.
Two important elements are also needed to design the cell membrane, which is phosphorus and sulfur.
Here is a mnemonic to remember respectively the six main chemical elements, present in living organisms: ONCH SP
Question 2: The right answer is A
Carbon forms the framework of all the organic molecules that make up living things, in association with oxygen, nitrogen, phosphate, and hydrogen, among others.
It is through photosynthesis that the carbon in the air in inorganic form - carbon dioxide (CO2, the famous greenhouse gas) - is captured by plants and transformed into organic matter. It is this organic form that allows herbivorous animals to make the sugars, lipids, and proteins that make them.
Question 3: The right answer is A.
Proteins and carbohydrates (not to mention lipids) are essential energy nutrients for the body. They are different but complementary.
Proteins are involved in the vast majority of the life of our cells, they are fundamental elements of life. They are helpful to our immune system to protect us from diseases. They also serve to transport molecules and regulate our hormones. High protein foods are dairy products, meat, eggs and fish (animal protein). But there are also many in cereals and legumes (vegetable proteins).
Finally, carbohydrates include sugars, considered as the first source of energy of the body. There is, of course, table sugar and all that is sweet, called simple carbohydrates, but there are also complex carbohydrates contained in cereals, potatoes, rice, or fruits and pulses. Carbohydrates are simply essential to the functioning of the brain. If you do not have enough sugar in your blood, your brain will gradually stop working: it is hypoglycemia.
Question 4: the right answer is D.
A polynucleotide is a polymer consisting of several nucleotide monomers covalently linked to form a chain. Nucleic acids such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) are polynucleotides.
DNA stands for deoxyribonucleic acid and is the carrier molecule for hereditary genetic information.
RNAs are molecules formed by the assembly of ribonucleotides, and which have very many functions in the cell.
Question 5: The right answer is C.
In addition to carbon and hydrogen, polynucleotides and proteins contain nitrogen and oxygen in large proportions.
Carbohydrates contain carbon, nitrogen, but also oxygen.
the lipids contain mainly carbon and hydrogen but contain oxygen in a very small proportion (one or two atoms) for example cholesterol (C27H46O) and palmitic acid (C16H32O2).
