Biology:2015:CBSE:[Delhi]:Set-III

Euchromatin is the transcriptionally active region of chromatin in a nucleus.

A geneticist interested in studying variations and patterns of inheritance in living beings prefers to choose organisms with short life cycles for experiments because it enables the geneticist to study many generations of those organisms in their short lifespans.

The illegal exploitation of biological material of a country by organisations or multinational companies without proper authorisation from the concerned country is known as biopiracy.

Industrial melanism was the reason for the increase in the population of dark-coloured moths along with the loss of lichens during industrialisation in England.
After industrialization, the tree trunks became darker with the deposits of soot and smoke. The number of dark moths increased as they were not easily visible to their predators however, the white-winged moths were easily picked up by the predators. Thus, dark ones were naturally selected and light ones fail to survive.

X-rays are potent mutagens and can cause adverse effects in children in the form of genital changes; i.e., they alter the genetic make-up of an organism.

Test-tube baby programme involves in-vitro fertilisation (IVF) which can be performed using two technologies:

• ZIFT or Zygote Intra-Fallopian Transfer: In this technique, the sperm from a male donor is fused with the ovum from a female donor in laboratory conditions and then it is transferred into the fallopian tube of a surrogate mother at 8-blastomere stage, for implantation and further development (known as intra-uterine transfer or IUT).
• GIFT or Gamete Intra-Fallopian Transfer: This technique involves transfer of an ovum collected from a donor into the fallopian tube of another female who cannot produce one, but can provide suitable environment for fertilisation and further development.

Many freshwater fish cannot survive in the marine environment as their bodies are not adapted to the marine environment. Freshwater fish lose body water because of the hypertonic environment that has a higher concentration of salt in the surrounding water, making their survival difficult.

Productivity: It is the rate of production of biomass at any trophic level at any given interval of time.

Gross productivity: It is the rate of production of organic matter by green plants per unit time per unit area. In other words, it is the total amount of productivity.

Net primary productivity: It is the difference between gross primary productivity and the loss due to respiration.Net primary productivity is the difference of gross primary productivity and respiratory loss.

Four objectives for improving the nutritional quality of different crops for the health benefits of the human population by the process of “biofortification” are:

• To improve protein content and quality
• To improve oil content and quality
• To improve vitamin content
• To improve micronutrient and mineral content