Answer the following questions.
a) What is pollination? With the help of a diagram explain self-pollination and cross-pollination
b) Distinguish between producers, consumers, and decomposers.
c) Describe briefly the mechanism of breathing in human beings.
d) Define the terms:
i) Uniform motion
ii) Non-uniform motion
e) Differentiate between concave and convex lenses.
f) How does transportation of water take place in plants?
g) With the help of a diagram explain the working of an electric bell.
) Describe the major factors causing the depletion of the water table.
i) How can we improve sanitation in public places?
Explain any four uses of the forests.
Answers
Answer:
a.) Pollination is a method where pollen grains are picked from an anther, which is the male part of a flower and transferred to the flower's female part called the stigma.
For diagram ,kindly refer to the attachment.
b)
Producers
All organisms which can prepare their own food by photosynthesis using the radiant energy of the sun absorbed by the chlorophyll of the leaves are called producers.Eg - green plants
Consumers
The organisms which consume the food produced either directly or indirectly are called consumers.
Consumers can be classified into primary, secondary and tertiary consumers based on their mode of nutrition.
All herbivores and some parasites are primary consumers. Example- rabbit, which eats grass.
Decomposers
The organisms which break down the dead remains and waste products of organisms are called decomposers.
Decomposers break down the complex organic substances into simple inorganic substances in the soil which is used by the plants.
Eg - Fungi
c.)The breathing mechanism involves two processes: Inspiration and Expiration
Inspiration
In the process of inspiration, there would be a contraction of muscles attached to the ribs on the outer side which pulls out the ribs and results in the expansion of the chest cavity.
Later, the diaphragm, contracts, moves downwards and expands the chest cavity resulting in the contraction of the abdominal muscles.
The expansion of the chest cavity produces a partial vacuum which sucks air into the lungs and fills the expanded alveoli.
Expiration
The expiration process is considered once after the gaseous exchange occurs in the lungs and the air is expelled out. This expulsion of air is called expiration.
During this process, muscles attached to the ribs contract, the muscles of the diaphragm and the abdomen relax which leads to a decrease in the volume of the chest cavity and increases the pressure of the lungs, causing the air in the lungs to be pushed out through the nose.
d. )i) Uniform motion: When an object covers equal distances in equal intervals of time, then its motion is said to be uniform.
ii) Non-uniform motion: When an object covers unequal distances in equal intervals of time, then its motion is said to be non-uniform
e.)Concave Vs Convex
Appearance
A concave lens is thinner in the middle and thicker at the edges.
A convex lens is thicker in the middle and thinner at the edges.
Also known as
Concave - It is also known as Diverging Lens .
Convex-It is also known as Converging Lens
Application
Concave - Used in glasses, some telescopes, spy holes in the doors, etc. It is also used for the correction of the problem in short sight
Convex - Used in the camera, focus sunlight, overhead projector, projector microscope, simple telescope, magnifying glasses, etc. It is also used for the correction of the problem in long sight.
Focal Length
Concave -Negative Focal Length
Convex - Positive Focal Length
Incident Rays
Concave - It diverges the incident rays away from the principal axis.
Convex - It converges the incident rays towards the principal axis.
f.)A group of special cells forming vascular tissue transport water qre called xylem tissues.
Xylem transports water and minerals obtained from the soil.
Vessels, tracheids of the roots, stems and leaves are connected to form a continuous system in xylem cells to transport water to all the parts of the plants.
Cells in the roots which are in contact with the soil take up ions which creates a difference of concentration between the roots and the soil and therefore water moves to the roots to eliminate the difference.
Water is moved into xylem of roots and from where it is pushed upward.
Plants use different mechanisms to pull water upwards through xylem like-
Water which is lost through stomata is replaced by water absorbed by the roots.
Evaporation of water from leaf creates a suction force which pulls water.
g.)A bell works with the principle of working of electromagnetism.
When the switch is pushed on, the circuit gets completed and the current starts flowing through the U-shaped electromagnet which creates a magnetic field in the core. This attracts the iron armature.
When the armature moves towards the electromagnet, the hammer strikes the gong and the bell rings.
As the armature moves towards the electromagnet, the contact with the adjustment screw breaks which breaks the closed circuit and stops the current. Now, when there is no current there is no electromagnetism and the armature returns to the original position. This making and breaking of the circuit of the electromagnet continue as long as the button remains pressed.
For diagram kindly refer to the attachment
the transference of pollen grains from the anther to the stigma is called pollination. self pollination is the transference of pollen from the stamens to the pistil of the same flower. cross pollination is the transference of pollen from the stamens of one flower to the pistil of another flower of the same kind of plant. if the speed of a body moving along a straight line remains constant then it is said to be in uniform motion . if the speed of a moving body is not moving along a straight line it is called non uniform motion .