Which of the following is not a constituent of DNA?

A. Purine

B. Phosphate

C. Cystocine

D. Deoxyribose

E. Uracil.

Which of the following best describes the homologous chromosomes? They are

A. a product of the division of a chromosome

B. two identical chromosomes from each parent

C. chromosomes arranged on spindle fibres during cell division

D. daughter chromatides formed during meiotic division

E. chromosomes during telophase of mitotic division

The haploid number of chromosomes in man is

A. 48

B. 46

C. 42

D. 24

E. 23

If a cross is made between a pure-breeding red flowered plant and a pure-breeding white flowered plant
where R is dominant for red flower and r is recessive for white, the most likely result of F generation will be

A. 75% red flowers and 25% white flowers

B. all red flowers

C. 75% white flowers and 25% red flowers

D. 50% red flowers and 50% white flowers

E. all white flowers

A man with blood group A (T^AP) married a woman with blood group O (pp). Which of the following is the
probable ratio of the blood groups of the offspring?

A. 1:1

B. 3:1

C. 2:1:1

D. 1:2:1

E. 4:1

Increasing specialization of structure and function among animals of the same class and order for survival in new and different environments is called

A. adaptive radiation

B. phylogeny

C. homology

D. analogy

E. ontogeny

When large numbers of organisms share limited space and resources the result is

A. immigration

B. commensalism

C. symbiosis

D. extinction

E. competition

The change in colour of the chameleon serves as a means of

A. attraction to the opposite sex

B. repulsion of the enemy

C. a camouflage from a predator

D. regulation of body temperature

Species can be defined as the group of organisms that

A. resemble each other and live in the same habitat

B. are of common origin and are always found together

C. resemble each other and can interbreed freely

D. resemble each other and occupy the same niche

E. are of common origin but cannot interbreed freely

Which of the following is not true about gene mutation? It

A. introduces new traits into a population

B. causes changes in the DNA

C. may have unnoticeable effect on the phenotype

D. always affects the chromosome number

E. is a source of new genes