Human Health and Disease — BIOLOGY STD 12 Science — Question

Write a short note on endosperm development.

Explain Competition as a population Interaction with suitable examples.

Read the following and answer any four questions from (i) to (v) given below: Siddharth is a chain smoker. He got into this habit in early adolescence due to peer pressure and gradually got addicted to this habit. Its now almost 20 years he is into the habit of smoking. Since few months he is experiencing pain in chest, shortness of breath, wheezing and chronic cough with phlegm. He seeked advice of a medical practitioner who diagnosed him with lung cancer. Based on the above information, answer the following questions.

1. What do you think is the possible carcinogen responsible for Siddharth's lung cancer?

1. Nitrosamines
2. Benzo(a)pyrene
3. Hydrazine
4. All of these

2. How is lung cancer diagnosed?

1. Computerised tomography scan
2. Sputum cytolog
3. Biopsy of lung tissue
4. All of these

3. From which of the following type of cancer is Siddharth suffering from?

1. Sarcoma
2. Carcinoma
3. Lymphoma
4. Leukemia

4. Select the correct statement.

1. Surgery, radiotherapy and chemotherapy can be used to treat lung cancer.
2. Chemotherapy involves the exposure of cancerous parts to X rays which destroy rapidly growing cancer cells.
3. Surgical removal of lung cancer tissue is suggested at advanced stage 4.
4. Monoclonal antibodies can effectively treat lung cancer and can cure it completely.

5. Assertion: Lung cancer if not treated at an early stage can spread to other initial organs of the body.

Reason: Cancer cell have uncontrolled proliferation and ability to invade new sites (metastasis).

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false

Early diagnosis is not possible by traditional methods for diagnosis and treatment- discuss in detail.

Read the following text carefully and answer the questions that follow:
Malaria and dengue fever are major mosquito-borne public health problems in tropical countries. The authors report a malaria and dengue co-infection in an 11-year-old boy who presented with sustained fever for 10 days. The physical examination revealed a flushed face, injected conjunctivae and left submandibular lymphadenopathy. His peripheral blood smear showed few ring-form trophozoites of Plasmodium falciparum. His blood tests were positive for dengue NS-1 antigen and IgM antibody, and negative for IgG antibody. After the initiation of antimalarial treatment with artesunate and mefloquine, his clinical condition gradually improved. However, he still had low-grade fever that persisted for 6 days. Finally, he recovered well without fluid leakage, shock or severe bleeding.
i. Name the fish that help in eradication of mosquito larvae.
ii. What is the reason of symptoms of malaria?
iii. Name the body parts and host in which following events takes place in life cycle of plasmodium.
a. asexual reproduction
b. sexual reproduction.
OR
Name some vector borne diseases and their vector.

Draw a schematic diagram of typical anatropous ovule and describe structure of megasporangium in detail.###With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.

Read the following text carefully and answer the questions that follow:
The following is the illustration of the sequence of ovarian events (a-i) in a human female.

i. Identify the figure that illustrates ovulation and mentions the stage of oogenesis it represents. (1)
ii. Name the ovarian hormone and the pituitary hormone that have caused the above-mentioned event. (1)
iii. Explain changes that occur in the uterus simultaneously in anticipation. (2)
OR
Draw a labelled sketch of the structure of a human ovum prior to fertilization. (2)

Why are vectors needed for replication of DNA during rDNA technology?

Read the following and answer any four questions front (i) to (v) given below:
Gene regulation is the mechanism of switching off and switching on of the genes depending upon the requirement of cells and the state of development. Gene regulation is of two types : negative and positive. In negative generegulation the genes continue expressing their effect till their activity is suppressed. Positive gene regulation is the one in which the genes remain non-expressed unless and until they are induced to do it. Operon model is a co-ordinated group of genes such as structural gene, operator gene, promoter gene, regulator gene which function together and regulate a metabolic pathway as a unit, e.g., lac operon, trp operon, ara operon, etc.

1. Regulation of gene expression occurs at the level of.

1. Transcription
2. Processing/splicing
3. Translation
4. All of these.

2. Inducible operon system usually occurs in A pathways. Nutrient molecules serve as B to stimulate production of the enzymes necessary for their breakdown. Genes for inducible operon are usually switched C and the repressor is synthesised in an D form.

S.no	A	B	C	D
(a)	anabolic	corepressor	on	inactive
(b)	anabolic	inducer	off	active
(c)	catabolic	inducer	off	active
(d)	catabolic	corepressor	on	inactive

3. An mRNA molecule transcribed from the lac operon contains nucleotide sequences complementary to.

1. Structural genes coding for the enzymes.
2. the operator region
3. the promotor region
4. the repressor gene.

4. Which statement correctly describes the control of transcription of the genes involved in the breakdown of lactose in Estherichia coli?

1. A repressor protein binds to the operator and the genes are switched on.
2. A repressor protein binds to the operator and the genes are switched off.
3. A transcription factor binds to the promoter and the genes are switched on.
4. A transcription factor binds to the promoter and the genes are switched off.

5. Function of catabolic activator protein in lac operon is.

1. To form mRNA
2. Help to bind RNA polymerase
3. Code for repressor
4. To activates lac gene when glucose is absent.