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Sonam’s questions in Biology


On Wed, Feb 24, 2010 at 11:28 AM, sonam kala wrote:

sir…
Thank you very much this unconditional help ………
here are some more questions in biology……

Our answers:

1.      Distinguish between acrocentic chromosome and submetacentric chromosome.
A centromere is a region of DNA typically found near the middle of a chromosome where two identical sister chromatids come in contact. It is involved in cell division as the point of mitotic spindle.

If arms’ lengths are unequal, the chromosome is said to be submetacentric. If the p (short) arm is so short that is hard to observe, but still present, then the chromosome is acrocentric There are thus two main differences which can be stated thus:
table1

2. Give reasons :
(i)     Impulses travel faster in myelinated neuron.

This can be explained with reference to the nodes of Ranvier. Between areas of myelin are non-myelinated areas called the nodes of Ranvier. Because fat (myelin) acts as an insulator, membrane coated with myelin will not conduct an impulse. So, in a myelinated neuron, action potentials only occur along the nodes and, therefore, impulses ‘jump’ over the areas of myelin – going from node to node in a process called saltatory conduction (with the word saltatory meaning ‘jumping’). Because the impulse ‘jumps’ over areas of myelin, an impulse travels much faster along a myelinated neuron than along a non-myelinated neuron.

3.    Tears and saliva have a germ killing effect because of the presence of Lysozyme and phospholipase

4. Choroid is the non-reflective coat of the eyeball.

5.    What is a labrynth?

The term refers to the internal ear. It is comprised of the cochlea and vestibular apparatus, and is responsible for hearing and balance.

6.    Name the smallest bone.

The smallest bone in the human body is the Stirrup (stapes) which is located in the middle ear. It helps amplify sound waves you hear.

7.      Define the term prophylaxis.

Prophylaxis:

The word “prophylaxis” is from the Greek language and means “an advance guard.”

A measure taken for the prevention of a disease or condition.

For example, dental prophylaxis consists of removing plaque and cleaning the teeth to prevent cavities and gum disease.

8.    RBC contain pigment called Haemoglobin

9.   The shortest phase of mitosis.
Anaphase is the shortest phase of mitosis.

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One Response to “Sonam’s questions in Biology”

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