Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

How is a cancerous cell different from normal cell?

How do biofertilisers enrich the fertility of the soil?

Refer to the figure given below and answer the questions that follow:

1. Recognize and explain the process by which Tasmanian wolf evolved.
2. Give one example of an animal that has evolved along with Tasmanian wolf.
3. Compare and contrast the two animals shown?

In which food would you find lactic acid bacteria? Mention some of their useful applications.

Write a short note on viability of seeds.###How long do the seeds remain alive after they are dispersed?

Answer the following questions:
What is amniocentesis and why there is a statutory ban on it?

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C; but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20mg/L, 8mg/L and 400mg/L, respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

1. Differentiate between analogous and homologous structures.
2. Select and write analogous structures from the list given below:

1. Wings of butterfly and birds.
2. Vertebrate hearts.
3. Tendrils of bougainvillea and cucurbita.
4. Tubers of sweet potato and potato.

Monocistronic structural genes in eukaryotes have interrupted coding sequences. Explain. How are they different in prokaryotes?