Cytosine thymine and uracil have a single ring structure and are classified as

Pyrimidine

Explanation:

This is because pyrimidine are one of the two types of heterocyclic nitrogenous bases of RNA and DNA. They include uracil, cytosine and thymine in RNA. They have single structure and have nitrogen at position 1 and ring at 3. Pyrimidine are present in Vitamins such as ribloflavin, folic acid and thiamine. Pyrimidine derivatives have characteristics that are antiviral, antibacterial, antifungal, sedative e.t.c.

ans.

gregor john mendel is known for study of inheritance in pea plants. he used garden pea plant for his study, having alternative traits for various characters. he performed cross-breeding in pea plants to check how characters are transmitted between parents to offspring, such as cross between pure tall and pure dwarf plant. mendel studied the inheritance patterns in pea plants for various generations.

thus, the correct answer includes options and f).

layer 3 is younger than layer 6.