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- Total number of questions : 20
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Cell Biology [ Question No: 1 To 20 ] :
Cytoplasm consists of all the fluid part :
Which enzyme of the following is used as a marker for lysosomal fraction ?
The main practical advantage of an immortalised line over a primary culture is that it
Consider the following statements about aseptic technique.
1. Work is carried out in a laminar flow hood.
2. Surfaces and gloves are disinfected before starting.
3. Antibiotics remove the need for careful technique.
State whether the following is true or false.
A cell that fails to undergo apoptosis when it should is at increased risk of becoming cancerous.
Apoptosis is best described as
State whether the following is true or false.
Mutations that make a signalling protein permanently active can cause cancer.
State whether the following is true or false.
Type 1 and type 2 diabetes both result from a failure to produce insulin.
Endocrine signalling is distinguished by the signal being
Independent assortment refers to
Apoptosis is triggered rather than repair attempted when
A cell that has withdrawn from the cycle and is not preparing to divide is said to be in
State whether the following is true or false.
X inactivation makes all the cells of a female mammal genetically identical in which X they express.
State whether the following is true or false.
Epigenetic marks such as DNA methylation change the underlying DNA sequence.
State whether the following is true or false.
A father passes his mitochondrial DNA to his children.
Assertion (A): Digestive enzymes are made and stored as inactive precursors.
Reason (R): Active proteases would digest the very cell that synthesised them.
State whether the following is true or false.
Plant cells lack a Golgi apparatus.
State whether the following is true or false.
Motor proteins can move in either direction along a filament depending on the cargo they carry.
The fluid mosaic model of membrane structure was proposed by
A cell that has lost the ability to divide but continues to function is best described as
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20
Cell Biology [ Question No: 1 To 20 ] :
Cytoplasm consists of all the fluid part :
Your Answer : (Not Answered)
Correct Answer : C
The cytoplasm is all the fluid part and structures within the plasma membrane except the nucleus.
Cytoplasm means the cytosol together with the organelles (mitochondria, endoplasmic reticulum, Golgi apparatus, ribosomes and so on) enclosed by the plasma membrane, excluding the nucleus. The nuclear contents are called the nucleoplasm.
The first option covers only the fluid, which is the cytosol. The second and fourth include everything within the membrane, and the fourth explicitly includes the nucleus; that whole living content is the protoplasm, not the cytoplasm.
Which enzyme of the following is used as a marker for lysosomal fraction ?
Your Answer : (Not Answered)
Correct Answer : C
The lysosomal marker enzyme is acid phosphatase.
In cell fractionation, each organelle is traced by an enzyme found only in it. Lysosomes contain acid hydrolases that work at their internal pH of about 5, and acid phosphatase is the classic marker. It was the enzyme whose latent activity led Christian de Duve to discover lysosomes.
Succinate dehydrogenase, of the inner mitochondrial membrane, is the marker for mitochondria, and pyruvate dehydrogenase is also mitochondrial. Phospholipases occur in many compartments and are not used as a lysosomal marker.
The main practical advantage of an immortalised line over a primary culture is that it
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: provides an unlimited and consistent supply of cells
An immortalised line divides indefinitely and can be expanded, frozen and shared, so experiments can be repeated by anyone with the same starting material. What is given up is fidelity: immortalisation and long culture change the cells, so they no longer behave exactly like the tissue they came from. That is the trade-off the next item refers to.
Consider the following statements about aseptic technique.
1. Work is carried out in a laminar flow hood.
2. Surfaces and gloves are disinfected before starting.
3. Antibiotics remove the need for careful technique.
Your Answer : (Not Answered)
Correct Answer : B
The first two are standard practice. The third is exactly the attitude that antibiotic use is criticised for encouraging, since a drug controls some organisms rather than preventing contamination. Technique, not chemistry, is what keeps a culture clean.
State whether the following is true or false.
A cell that fails to undergo apoptosis when it should is at increased risk of becoming cancerous.
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: True
Apoptosis is one of the principal defences against cancer: a cell with irreparable DNA damage, or one dividing when it should not, is normally instructed to die. Losing that response allows damaged cells to persist and accumulate further mutations, which is why evading apoptosis is counted among the hallmarks of cancer and why p53, which triggers it, is the most frequently mutated gene in human tumours.
Apoptosis is best described as
Your Answer : (Not Answered)
Correct Answer : A
The cell dismantles itself according to a genetic programme and is removed without disturbing its neighbours. Death by injury follows an entirely different and far messier course. The two are distinguished by how the cell dies, not by whether it dies.
State whether the following is true or false.
Mutations that make a signalling protein permanently active can cause cancer.
Your Answer : (Not Answered)
Correct Answer : C
A component locked in its on state drives division whether or not a growth signal has arrived. The Ras protein is the classic case, and mutations in it are found in a large fraction of tumours. Roughly a quarter of all human cancers carry a Ras mutation.
State whether the following is true or false.
Type 1 and type 2 diabetes both result from a failure to produce insulin.
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: False
The two are different diseases. Type 1 is autoimmune destruction of the pancreatic beta cells, so insulin genuinely is not produced and must be replaced. Type 2 is primarily resistance: insulin is produced, often in increased amounts at first, but the target cells respond poorly, and secretion may fail later as the beta cells are exhausted. The distinction determines the treatment entirely.
Endocrine signalling is distinguished by the signal being
Your Answer : (Not Answered)
Correct Answer : B
Hormones reach the whole body but affect only cells carrying the right receptor. This is why one circulating molecule can produce quite different effects in different tissues. Adrenaline dilates some blood vessels and constricts others for this reason.
Independent assortment refers to
Your Answer : (Not Answered)
Correct Answer : A
Which member of each pair goes to which pole is decided independently for every pair, so the combinations multiply. Crossing over is the separate mechanism that shuffles within a chromosome. The two mechanisms act at different scales and multiply together.
Apoptosis is triggered rather than repair attempted when
Your Answer : (Not Answered)
Correct Answer : B
Removing a badly damaged cell protects the organism from the mutations it would otherwise pass on. p53 makes this decision, arresting the cycle first and choosing death only if repair fails. The choice between arrest and death is one of the most consequential a cell makes.
A cell that has withdrawn from the cycle and is not preparing to divide is said to be in
Your Answer : (Not Answered)
Correct Answer : C
Most cells in an adult body are in this state, some able to re-enter the cycle when signalled and others permanently so. Neurons and cardiac muscle cells are the classic examples of the permanent case. Damage to those tissues is therefore repaired poorly if at all.
State whether the following is true or false.
X inactivation makes all the cells of a female mammal genetically identical in which X they express.
Your Answer : (Not Answered)
Correct Answer : D
The choice is made independently in each cell early in development and then inherited, so a female is a mosaic of two populations. The patches of a tortoiseshell cat are the visible result. Each patch descends from one early cell and its inactivation choice.
State whether the following is true or false.
Epigenetic marks such as DNA methylation change the underlying DNA sequence.
Your Answer : (Not Answered)
Correct Answer : B
They alter how a sequence is read without changing a single base, which is precisely what the word epigenetic means. This is why such marks can be reversed while a mutation cannot. That reversibility is what makes epigenetic marks attractive as drug targets.
State whether the following is true or false.
A father passes his mitochondrial DNA to his children.
Your Answer : (Not Answered)
Correct Answer : B
The sperm contributes almost no mitochondria, and the few that enter are destroyed, so inheritance is effectively maternal. This is why mitochondrial disease can pass from a mother to all her children but never from a father.
Assertion (A): Digestive enzymes are made and stored as inactive precursors.
Reason (R): Active proteases would digest the very cell that synthesised them.
Your Answer : (Not Answered)
Correct Answer : C
Both are true and the reason gives the necessity plainly: the safeguard is a matter of self-protection, and pancreatitis is precisely what follows when it fails and the enzymes activate too early. The tissue then digests itself, which makes the condition a serious one.
State whether the following is true or false.
Plant cells lack a Golgi apparatus.
Your Answer : (Not Answered)
Correct Answer : A
They have many separate Golgi stacks, called dictyosomes, which are especially busy making the polysaccharides of the cell wall. Their arrangement differs from the single stack of many animal cells but the organelle is certainly present.
State whether the following is true or false.
Motor proteins can move in either direction along a filament depending on the cargo they carry.
Your Answer : (Not Answered)
Correct Answer : B
Correct answer: False
A given motor has a fixed directionality determined by its own structure: kinesins generally walk towards the microtubule plus end and dyneins towards the minus end, whatever they are carrying. Cargo that must travel both ways carries motors of both types, and the direction of transport is set by which of them is active rather than by the cargo itself.
The fluid mosaic model of membrane structure was proposed by
Your Answer : (Not Answered)
Correct Answer : A
Their 1972 model described proteins floating in and through a fluid lipid bilayer rather than coating it as a continuous sheet. Danielli and Davson had earlier proposed the protein sandwich model that this replaced, and Gorter and Grendel first showed the lipid was a bilayer.
A cell that has lost the ability to divide but continues to function is best described as
Your Answer : (Not Answered)
Correct Answer : B
Correct answer: terminally differentiated
A terminally differentiated cell has left the cell cycle permanently and devotes itself to its specialised function - a neuron, a cardiac muscle cell, a mature red blood cell. It is neither damaged nor dying, which distinguishes it from a genome failure and from apoptosis, and it is the opposite end of the scale from the totipotent cell that has differentiated into nothing at all.
Marks
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20