How do storage grain losses occur?
Both biotic and abiotic factors play an important role in the spoilage of the stored seeds. Biotic factors such as insects or pests that cause direct damage by feeding on seed. Abiotic factors such as temperature, light, moisture, etc., also affect the seed. They decrease the germinating ability of the seeds and make them unfit for future use by farmers. Unpredictable occurrence of natural calamities such as droughts and floods also causes destruction of crops.
Popular Questions of Class 9 Science
- Q:-
Abdul, while driving to school, computes the average speed for his trip to be 20 km h-1. On his return trip along the same route, there is less traffic and the average speed is 40 km h-1. What is the average speed for Abdul’s trip?
- Q:-
An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.
- Q:-
A driver of a car travelling at 52 km h-1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h-1 in another car applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?
- Q:-
Fig 8.11 shows the distance-time graph of three objects A,B and C. Study the graph and answer the following questions:
Fig. 8.11
(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?
(c) How far has C travelled when B passes A?
(d) How far has B travelled by the time it passes C? - Q:-
Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m s-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?
- Q:-
Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?
- Q:-
Two objects of masses 100 g and 200 g are moving along the same line and direction with velocities of 2 m s-1 and 1 m s-1, respectively. They collide and after the collision, the first object moves at a velocity of 1.67 m s-1. Determine the velocity of the second object.
- Q:-
How do poriferan animals differ from coelenterate animals?
- Q:-
The speed-time graph for a car is shown is Fig. 8.12.
Fig. 8.12
(a) Find how far does the car travel in the first 4 seconds. Shade the area on the graph that represents the distance travelled by the car during the period.
(b) Which part of the graph represents uniform motion of the car? - Q:-
How are sol, solution and suspension different from each other?
Recently Viewed Questions of Class 9 Science
- Q:-
Where is apical meristem found?
- Q:-
Convert the following temperatures to the Celsius scale.
(a) 300 K (b) 573 K.
- Q:-
Give reasons for the following observation:
The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.
- Q:-
On what bases are plants and animals put into different categories?
- Q:-
Isotopes of an element have
(a) the same physical properties
(b) different chemical properties
(c) different number of neutrons
(d) different atomic numbers. - Q:-
What happens to the force between two objects, if
(i) the mass of one object is doubled?
(ii) the distance between the objects is doubled and tripled?
(iii) the masses of both objects are doubled? - Q:-
Why is the weight of an object on the moon 1/6th its weight on the earth?
- Q:-
How is soil formed?
- Q:-
What is the major source of fresh water in the city/town/village where you live?
- Q:-
Differentiate between homogeneous and heterogeneous mixtures with examples.
- NCERT Chapter