Evolution — BIOLOGY STD 12 Science — Question

How does the transmission of each of the following diseases take place?

1. Amoebiasis.
2. Malaria.
3. Ascariasis.
4. Pneumonia.

Explain the process of separation and isolation of DNA segments from gel electrophoresis technique.

What do you understand by energy flow in an ecosystem? Explain the flow of energy through different trophic levels. Draw a diagram of a food chain.

1. How is artificial hybridisation considered a crop improvement programme?
2. Explain the process of artificial hybridisation, if

1. Female parent bears bisexual flowers.
2. Female parent bears unisexual flowers.

What is placenta? Draw well labelled diagram of human embryo showing placenta in uterus and also write its four functions.

Describe the following: Bioreactor

Answer the following questions:
Name the hormones secreted and write their functions:

1. By corpus luteum and placenta (any two) .
2. During Follicular phase and parturition.

The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.

	Name of the Disease	Causative organism	Symptoms
i.	Ascariasis	Ascaris	________
ii.	________	Trichophyton	Appearance of dry, scaly lesions on various parts of the body.
iii.	Typhoid	________	High fever, weakness, headache, stomach pain, constipation.
iv.	Pneumonia	Streptococcus pneumoniae	________
v.	________	Rhino viruses	Nasal congestion and discharge, sorethroat, cough, headache.
vi.	Filariasis	________	Inflammation in lower limbs.

Answer the following questions:
State and explain the law of segregation as proposed by Mendel in a monohybrid cross.