What would happen to the life of a cell if there was no Golgi apparatus?
The Golgi apparatus consists of stacks of membrane-bound vesicles whose functions are as follows:
Without the golgi apparatus, the cells will be disabled from packing and dispatching materials that were produced by the cells. The golgi apparatus is also involved in the formation of cells. Hence, in the absence of golgi apparatus, cells will not be produced.
Which organelle is known as the powerhouse of the cell? Why?
Mitochondria are known as the powerhouse of the cell. It is because it releases the energy required for different activities of life. Mitochondria releases energy in the form of ATP(Adenosine triphosphate) molecules, essential for numerous chemical activities of life. Hence ATP is often referred to as ‘energy currency of the cell’.
What is osmosis?
The process of movement of a water molecule from a region of higher concentration to a region of lower concentration through a semipermeable membrane is known as osmosis.
Carry out the following osmosis experiment:
Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) Keep cup A empty
(b) Put one teaspoon sugar in cup B
(c) Put one teaspoon salt in cup C
(d) Put one teaspoon sugar in the boiled potato cup D.
Keep these for two hours. Then observe the four potato cups and answer the following:
(i) Explain why water gathers in the hollowed portion of B and C.
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
(i) Water accumulates in the hollowed portions of B and C as a difference in the water concentration
is observed. Thereby, endosmosis occurs as the cells act as a semipermeable membrane.
(ii) Potato A is essential in this experiment as it is significant to compare different scenarios seen in
potato cups B, C and D. The potato A in this experiment clearly shows that the potato cavity on its
own cannot bring about water movement.
(iii) Cup in A does not show any change in the water flow concentration for osmosis to occur, which
requires the concentration to be higher than the other. Cells in cup D are dead, thus there is no
existence of a semipermeable membrane for water flow. Consequently, osmosis does not occur.
Which type of cell division is required for growth and repair of body and which type is involved in formation of gametes?
There are two ways in which a cell divides:
Mitosis is the type of cell division that is involved in the growth and repair of body whereas meiosis is a type of cell division which results in the formation of gametes.
In what direction does the buoyant force on an object immersed in a liquid act?
The buoyant force on an object that is immersed in a liquid will be in a vertically upward direction.
Why a block of plastic when released under water come up to the surface of water?
The density of plastic is lesser than that of water. Therefore, the force of buoyancy on plastic block will be greater than the weight of plastic block. Hence, the acceleration of plastic block is going to be in the upward direction. So, the plastic block comes up to the surface of water.
The volume of 50 g of a substance is 20 cm3. If the density of water is 1 g cm–3, will the substance float or sink?
To find the Density of the substance the formula is
Density = (Mass/Volume)
Density = (50/20) = 2.5g/cm3
Density of water = 1g/cm3
Density of the substance is greater than density of water. So the substance will sink.
The volume of a 500 g sealed packet is 350 cm3. Will the packet float or sink in water if the density of water is 1 g cm–3? What will be the mass of the water displaced by this packet?
Density of sealed packet = 500/350 = 1.42 g/cm3
Density of sealed packet is greater than density of water
Therefore the packet will sink.
Considering Archimedes Principle,
Displaced water volume = Force exerted on the sealed packet.
Volume of water displaced = 350cm3
Therefore displaced water mass = ? x V
= 1 × 350
Mass of displaced water = 350g
A girl is sitting in the middle of a park of dimension 12 m × 12 m. On the left side of it there is a building adjoining the park and on right side of the park, there is a road adjoining the park. A sound is produced on the road by a cracker. Is it possible for the girl to hear the echo of this sound? Explain your answer.
Echo can be heard if the gap between the original sound and reflected sound received by the listener is around 0.1 sec.
Sound Velocity × time interval
= 344×0.1
= 34.4 m
Here sound reflects from the building and then reaches the girl which is much smaller than the required distance. Hence echo cannot be heard.
Science (7568)
Maths (4467)
Technology (239)
English (170)
Grades