DNA is composed of nucleotides, which are composed of three parts:
1. A five carbon carbohydrate (pentose)
Pentose is classified as a monosaccharide (simple carbohydrate), and its molecular formula is represented by 
. They are water soluble molecules with sweet taste. Monosaccharides may have from three carbon atoms (trioses) to six (hexoses). In DNA is present pentose (5 carbon atoms)
2. A nitrogenous base
Nitrogenous bases are ring-shaped compounds that contain nitrogen in their molecular structure. They are classified into two groups: purines and pyrimidines
The purine bases are adenine (A) and guanine (G). They are larger and contain more than one ring in their structure,.
The pyrimidines, cytosine (C), uracil (U) and thymine (T), are smaller and composed of a single ring.
3. One or more phosphate groups
A phosphate consists of a trivalent anion that contains one phosphorus atom and four oxygen atoms. Its molecular formula is expressed by 
.
Answer:
Its cells have thick, hard walls.
Explanation:
Answer:
3) The correct answer would be the third option.
Enzymes are biocatalysts which increases the rate of a biochemical reaction is decreasing the activation energy required by the reaction.
The substrate binds to the active site of the enzyme to form an enzyme-substrate complex. It is then converted to enzyme-product complex. Lastly, the product is released and the enzyme is ready for a new cycle of reaction.
4) The correct answer would be cohesion.
Cohesion or cohesive force refers to the attractive force by which like-molecules are stick together.
For example, water molecules are stick together to form droplets.
Besides producing sugar for itself a plant also needs to absorb nitrogen to build proteins, salts to make concentration gradients and potassium to make enzymes.
<u>Explanation:</u>
Plant sugar is glucose and plants produce it by the process of photosynthesis making use of energy from sunlight, carbon dioxide absorbed from the atmosphere and the presence of chlorophyll in its parts. Plants also require components other than this. Nitrogen is essential to make proteins and it cannot be directly absorbed from the atmosphere but has to be absorbed from the soil.
Potassium is an essential component which is absorbed from the soil. It facilitates the activation of enzymes which play a crucial role in plant metabolism. When plants lack potassium they won’t have enough energy for proper growth and will have poorly formed roots and weak stems.
How does a new hypothesis replace an older explanation of something in the natural world? To understand this let us look at one of the classical example of geocentric theory and heliocentric theory. The geocentric theory states the Earth is at the centre of the solar system and the Sun, Moon, and all the other planets revolve around it. This ancient theory failed to explain the phenomenon like the phases of Moon, solar eclipse and lunar eclipse. The modern heliocentric theory which states that the Sun is at the centre of solar system, and all the planets including the Earth revolve around it. This theory was able to explain all the phenomenons unlike the geocentric theory. Hence the heliocentric theory replaced the geocentric theory.
