The answer is D. Carbon cycle
Mutations are changes that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke.
They increase the genetic variation within a species because they can create entirely new alleles in a population, random mating, random fertilization, and recombination between homologous chromosomes during meiosis which reshuffles alleles within an organism's offspring.
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The period of Convalescence is the time during which the person regains health and fully recovers.
Explanation:
- Diseases that can spread from one person to other are called infectious disease.
- Disease development is divided into Incubation period, Prodromal period, period of illness, Decline period, and period of Convalescence.
- During incubation period the pathogen enters the host body and starts multiplying itself. But the signs of diseases are unnoticeable.
- Then comes the prodromal period, when the pathogen keeps multiplying itself and some signs of disease are observed but they are not obvious
- After the prodromal period comes the period of illness when the patient exhibits obvious signs of sickness.
- As the period of illness is over the symptoms of disease start to cease and the the number of pathogen decrease in body.This period is the period of decline.
- Finally comes the period of Convalescence when the person returns to his pre-disease state and is completely healthy. (except irreversible damage caused by the disease)
Answer:
All of the answer options are correct.
Explanation:
Chargaff contributed in understanding the structure and composition of DNA with his discoveries. He discovered that purine and pyrimidine bases are in equal amounts in a DNA molecule. He also discovered that amount of Adenine base (A) is equal to amount of Thymine base (T). It means that A pairs with T. Since A is a purine and T is a pyrimidine it also implies that purine base pairs with a pyrimidine base. This conclusion can also be arrived by taking in consideration the other base pair which is G (purine) and C (pyrimidine).
