Question

The organelle known as the powerhouse (provides energy molecules) of the cell is the

Question 1 options:

	vacuole
	nucleus
	mitochondrion
	ribosome

The organelle known as the control centre (brain, library) of the cell is the

Question 2 options:

	endoplasmic reticulum
	mitochondrion
	nucleus
	chloroplast

Molecules that are "water-fearing" are

Question 3 options:

	non-polar/hydrophobic
	polar/hydrophobic
	non-polar/hydrophilic
	polar/hydrophilic

A glass can be filled with water above the rim without spilling due to

Question 4 options:

	hydrophobic interactions
	covalent bonds
	ionic bonds
	hydrogen bonds

Answer 1

Ans.

1). Power house of cell ;

• Tiny organelles known as mitochondria release energy from food in our body.
• This process of energy generation is called as cellular respiration.
• Due to this energy producing role of mitochondria in the body, it is also called as the powerhouse of the cell.
• The quantity of mitochondria in a cell depends upon it's energy requirement for eg. cells which requires more energy will have thousands of mitochondria.
• In the process of ageing and neurodegenerative diseases also, mitochondria have a critical role.

2). Control centre of cell;

• There are many membrane bound structure found in cell and are known as cell organelle which have distinctive structures and functions.
• Nucleus is also a membrane bound cell organelle present in almost all of the eukaryotic cells.
• It consists of structures that are critical for normal cell functions such as nucleolus and chromosomes.
• Nucleus is the largest cell organelle and plays the role of control center of the cell.
• It also acts as the storehouse of cell's DNA (library) within body.

3). Water-fearing ;

• Some molecules don't have any kind of charges on themselves and are known as non-polar molecules.
• These molecules can not attract water i.e. water insoluble.
• Most part of the non-polar molecules will form a boundary upon contacting water and exists as a seperate unit.
• Such type of molecules which upon contacting water do not dissolve and make a boundary are called as hydrophobic molecules.
• Therefore, "water-fearing" molecules are also called as non-polar/hydrophobic molecules.

4).

• Water is composed of molecules which are polar in nature, having positive or negative charges.
• Because of the attraction between opposite charges, each of these molecules remain associated with one another.
• This type of attraction between molecules of same kind is known as cohesion.
• Due to the presence of hydrogen bonds, there is a strong force of cohesion between the molecules of water.
• These cohesive forces between the molecules are reason the of surface tension which provides the surface of liquids a tendency to resist the rupture upon being placed in stressful conditions or under tension.