41.

Consider the following statements about DNA replication.

I. A replisome is the largest functional unit in DNA replication factories.

II. RNA polymerase complexes are responsible for transcribing the newly synthesised RNAs into their mature form.

III. DNA polymerases add new deoxyribonucleotides to the 3' end of a DNA strand.

IV. A replication bubble is a region of single stranded DNA that arises due to unwinding of DNA in same direction by primase

Choose the incorrect statement(s)

• I and II

• III and IV

• I, II and IV

• I, II, III and IV

The process in which mature differentiated cells reverse to meristematic activity to form callus is called

• redifferentiation

• dedifferentiation

• cyto-differentiation

• differentiation

Endothecium and tapetum are formed from

• primary sporogenous tissue

• primary parietal layer

• primary parietal layer and sporogenous tissue respectively

• sporogenous tissue and primary parietal layer respectively

Which of the following is an example of a defence used by plants against herbivorous?

I. Production of caffeine, tannin, quinine.

II. More production of non-woody tissues.

III. Production of hairs, thorns, spines.

IV. Production of hormones like chemicals that interfere with insect metamorphosis.

Select the correct codes

• I and II

• II, III and IV

• I, II and III

• I, III and IV

Embryo rescue is resorted to

• obtain new generation of plants quickly

• to reduce chance of seedling growth

• ensure growth of interspecific hybrids

• induce somaclonal variations

In sweet pea, C and P genes are essential for flower colour. In absence of either or both the genes, the flowers are white. What will be the percentage of coloured flowers in the offspring of cross Ccpp x ccPp?

• 75%

• 25%

• 80%

• 50%

Apomictic embryos in citrus arise from

• synergids

• maternal sporophytic tissue in ovule

• antipodal cell

• haploid cell

Following are the statements regarding sexual reproduction in flowering plants.

I. Parthenium is a plant that causes pollen allergy.

II. If tapetum is destroyed, then unfeasible male gametophytes are produced.

III. Egg apparatus has 3 synergids and 2 antipodal cells.

IV. Megaspore is the first cell of gametophytic generation.

Choose the incorrect option.

• I and II

• II and III

• III and IV

• I and IV

Reproductive isolation mechanism prevent interbreeding of naturally sympatric population. Given below are categories of isolating mechanisms. Choose the correct name for isolation when potential mates occupy overlapping ranges but reproduce at different times of the year.

• Ecological isolation

• Behavioural isolation

• Temporal isolation

• Mechanical isolation

A women with albinic father marries an albinic man. The proportion of her progeny is

• 2 normal : 1 albinic

• All normal

• All albinic

• 1 normal : 1 albinic