Human Reproduction — BIOLOGY STD 12 Science — Question

Of the four major causes for the loss of biodiversity (Alien species invasion, habitat loss and fragmentation, over-exploitation and co-extinctions which according to you is the major cause for the loss of biodiversity? Give reasons in support.

What is apomixis and what is its importance?

How does the disease spread? Write briefly.

Describe in detail about food chain and food web existing in an ecosystem.

Explain the principle of insertional inactivation by giving a suitable example.

Explain with the help of one example how genetically modified plants can:

1. Reduce usage of chemical pesticides.
2. Enhance nutritional value of food crops.

What are sexually transmitted diseases? Write the names of these diseases. Also describe the two diseases with special reference on their mode of transmission symptoms and the preventive measures against them.

Your school’s athletic team along with the athletic teams from different schools reach the venue two days before the inter district school athletic event was to be held. A day before the competition, a team of officials from an agency arrive and ask for blood and urine samples from all the participating athletes.

1. Would you support or object to this sample collection? Provide explanation to your answer.
2. Write a note that you would like to read out to your team-mates to explain the purpose of this visit of these officials.

Fill in the blanks in the different column of the table given below:

Disease	Casual organisms	Medium of transfer	Symptoms
Amoebiasis	Entamoeba histolytica	a	Diarrhoea
Typhoid	b	Contaminated food	Sustained high fever
c	Plasmodium	Bite of infected female Anopheles mosquito	Chill and high fever
Pneumonia	Steptococcus	d	Fever and cough

Describe in detail the origin and evolution of human?