Question

1. The powerhouse of the cell that generates ATP is

1. Peroxisomes
2. Mitochondria
3. Plasma membrane
4. Golgi body

2. The connective tissue disorder due to a mutation on chromosome 15 causing weak joints and ligaments is

1. Tay-sachs disease
2. Marfan syndrome
3. Phenylketonuria
4. Neurofibromatosis

3. Carcinogenesis involves three stages. Which stage involves the induction of unregulated accelerated growth in susceptible cells?

1. Initiation.
2. Transduction.
3. Promotion.
4. Progression.

4. Necrotic death of brain tissue usually produces

1. Fat necrosis.
2. Caseous necrosis.
3. Liquefactive necrosis.
4. Coagulative necrosis.

5. Lack of exercise during an illness may cause skeletal muscle to undergo:

1. hypertrophy
2. dysplasia
3. atrophy
4. necrosis

6. Metaplasia is

1. The disorganization of cells into various sizes, shapes, and arrangements.
2. The replacement of one differentiated cell type with another.
3. The transformation of a cell type to malignancy.
4. An irreversible cellular adaptation.

Answer 1

Q1..Power house of cell that generate ATP is mitochondria_derived from oxidative phosphorylation.Mitochondria oxidize substrate to CO2,transferring the high energy electrons from the original molecule(eg_sugar)to molecular oxygen,and generating the low energy electrons of water. The oxidation of various metabolites derives hydrogen ion(proton) pumps that transfer H+ from the core matrix into the intermembrane space.As the H+ ions flow back down their electrochemical gradient,the energy releasd is used in the synthesis of ATP..Plasma membrane is the lipid bilayer covering of cell.Golgi apparatus is for packing and transportation of proteins.Peroxisomes helps in breakdown of fattyacids,generating H2O2 in this process. Thus answer is mitochondria.

Q2..Marfan syndrome is a disorder of connective tisdue,manifested mainly by changes in skeleton,eye and cardiovascular system.It results from an inherited defect in an extracellular glycoprotein called fibrillin1(FBN1 gene mapped on chromosome 15q21.1)_loss of structural support in microfibril rich connective tissue and excessive activation of TGF_beta signaling.

Taysachs diseasevalso results from mutation in chr 15 but it is a lysosomal storage disorder_accumulation of gangliosides.Phenylketonuria is a metabolic disorder_autosomal recessive condition.

Neurofibromatosis is an autosomal dominant condition (chromosome 17)affect brain,spinal cord and nerves.

Q4..Necrosis of brain tissue produces liquifactive necrosis.(dissolution of tissues_creamy yellow necrotic material).An infract in areas other than brain produces coagulative necrosis.Fat necrosis occours in adipose tissues(traumatic and enzymatic).Caseous necrosis in lungs as a result of tuberculosis.

Q5..Lack of exercise can cause muscle atrophy_ called disuse atrophy.It is due to reduction in size and number of cells in muscle.It is a type of adaptation,happens due to apoptosis of muscle fibre cells.

Hypertrophy is increase in size of cells resulting in increased size of the organ.dysplasia is disordered growth.Necrosis is an irreversible injury or cell death.

Q6..Metaplasia ia a reversible change in which one differentiated cell type is replaced by another cell type.(adaptive response in which one cell type which is sensitive to a particular stress is replaced by another cell type that is better able to withstand the adverse environment.metaplasia can lead to premalinant conditions.Thus option B is correct.