Human Reproduction — BIOLOGY STD 12 Science — Question

What are genetically modified organisms? Name two factors on which their behaviour depends.

Pollen banks are playing a very important role in promoting plant breeding programme the world over. How are pollens preserved in the pollen banks? Explain. How are such banks benefitting our farmer? Write any two ways.

Explain the zygote intra fallopian transfer technique (ZIFT). How is intra uterine transfer technique (IUT) different from it?

The base sequence in one of the strands of DNA is TAGCATGAT

1. Give the base sequence of its complementary strand.
2. How are these base pairs held together in a DNA molecule?
3. Explain the base complementarity rules. Name the scientist who framed this rule.

What is primary productivity? Give brief description of factors that affect primary productivity.

Study the table showing the population interaction between species Z and Y respectively. Assign the appropriate +/- signs for A, B, D, E and respective interactions for C and F.

Species 'Z'	Species 'Y'	Name of Interaction
A	B	Mutualism
-	-	C
D	E	Parasitism
+	O	F

Outline salient features of carbon cycling in an ecosystem.

Explain the difference between commensalism and mutualism types of interactions, with the help of a suitable example of each.

Show with the help of diagram the stages in which a pollen mother celll transforms into a pollengrain.

Using a Punnett Square, workout the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.