How would you choose between two characteristics to be used for developing a hierarchy in classification?
For classifying an organism in a hierarchical model, we choose the fundamental characteristic among several other characteristics. For example, plants differ from animals in having chloroplast and lacking locomotion. But, only locomotion is considered as the basic or fundamental feature that is used to distinguish between plants and animals. This is because the absence of locomotion in plants gave rise to many structural changes such as the presence of a cell wall for protection, and the presence of chloroplast for photosynthesis.
How do poriferan animals differ from coelenterate animals?
Explain the basis for grouping organisms into five kingdoms.
Explain how animals in Vertebrata are classified into further subgroups.
Which organisms are called primitive and how are they different from the so-called advanced organisms?
How do gymnosperms and Angiosperms differ from each other?
Give three examples of the range of variations that you see in life-forms around you.
What are the major divisions in the Plantae? What is the basis for these divisions?
How do annelid animals differ from arthropods?
Which do you think is a more basic characteristic for classifying organisms?
(a) the place where they live.
(b) the kind of cells they are made of. Why?
What are the differences between amphibians and reptiles?
Which of the following has more inertia: (a) a rubber ball and a stone of the same size? (b) a bicycle and a train? (c) a five-rupees coin and a one-rupee coin?
State the universal law of gravitation.
Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of perfume.
A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (Fig. 11.3). Let us take it that the force acts on the object through the displacement. What is the work done in this case?
What is meant by a pure substance?
How does the sound produced by a vibrating object in a medium reach your ear?
In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium observations are in agreement with the law of conservation of mass.
sodium carbonate + ethanoic acid → sodium ethanoate + carbon dioxide + water
What are canal rays?
State any two conditions essential for good health.
How is our atmosphere different from the atmospheres on Venus and Mars?
Why is it difficult to hold a school bag having a strap made of a thin and strong string?
Find the energy in kW h consumed in 10 hours by four devices of power 500 W each.
Can you name the two organelles we have studied that contain their own genetic material?
Define 1 J of work.
Who discovered cells, and how?
State any two conditions essential for good health.
An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?
The earth and the moon are attracted to each other by gravitational force. Does the earth attract the moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth? Why?
Convert the following temperatures to the Kelvin scale.
(a) 25°C (b) 373°C.
Name A,B,C,D,E and F in the following diagram showing change in its state