Diversity in Living Organisms 2

Question 1 ( 1.0 marks)

A certain plant ‘X’ shows the presence of vascular tissue, but does not produce seeds. To which division does plant ‘X’ belong?

Solution:

Pteridophytes

Question 2 ( 1.0 marks)

Fill in the blanks.

Reptiles have __________-chambered heart, while fishes have __________-chambered heart.

Solution:

Reptiles have three-chambered heart, while fishes have two-chambered heart.

Question 3 ( 1.0 marks)

Give two examples of cartilaginous fishes.

Solution:

Scoliodon and shark

Question 4 ( 2.0 marks)

Differentiate between bilateral symmetry and radial symmetry.

Solution:

-	Radial Symmetry	-	Bilateral Symmetry
(i)	If the body of an animal is divided into two equal parts by cutting it in any plane passing through the centre of its body, then the body of the animal is said to have radial symmetry.	(i)	If the body of an animal is divided into left and right halves by one plane only, then the body of the animal is said to have bilateral symmetry.
(ii)	Animals of phylum coelenterate are radially symmetrical.	(ii)	Animals of phylum helminthes and higher phyla are bilaterally symmetrical.

Question 5 ( 2.0 marks)

How is classification related to evolution?

Solution:

(i) Classification is closely related to evolution since most of the present-day life forms have arisen by an accumulation of changes that have allowed them to survive better.

(ii) Some organisms have not changed much and have ancient body designs. Such organisms are called primitive or lower organisms. Advanced or higher organisms have comparatively recent body designs.

(iii) So, complexity increases over the evolutionary time.

Question 6 ( 2.0 marks)

What are oviparous mammals? Give examples.

Solution:

Egg-laying mammals are called oviparous mammals.

E. g.Platypus, Echidna, etc

Question 7 ( 3.0 marks)

Differentiate between the following.

(i ) Fishes and amphibians
(ii) Amphibians and reptiles

(iii) Cartilaginous and bony fishes

Solution:

(i)

-	Fishes	-	Amphibians
(a)	They are exclusively aquatic.	(a)	Only the larval stage is aquatic.
(b)	Skin is covered with scales.	(b)	Scales are absent.
(c)	Heart is two chambered.	(c)	Heart is three chambered.

(ii)

-	Amphibians	-	Reptiles
(a)	They have dual mode of life − larva is aquatic, while the adult is terrestrial.	(a)	They are completely terrestrial.
(b)	Scales are absent.	(b)	Body is covered with scales.
(c)	They lay eggs on water.	(c)	They lay eggs on land.

(ii)

-	Bony fishes	-	Cartilaginous fishes
(a)	Their skeleton is composed partly or wholly of bones.	(a)	Their skeleton is made entirely of cartilage.
(b)	E.g., tuna, sea horse, etc.	(b)	E.g., torpedo, shark, etc.

Question 8 ( 3.0 marks)

Give reasons for the following.

(i) Prokaryotes are unicellular, while eukaryotes can be unicellular or multicellular.

(ii) Locomotion is the ultimate criteria for classifying living organisms as plants and animals.

Solution:

(i) Due to the absence of membrane-bound nucleus and other organelles, different biochemical pathways and cellular processes cannot be carried out efficiently in prokaryotes. On the other hand, in eukaryotes, membrane-bound organelles carry out cellular processes in isolation from each other, and cells have the capacity to make up a multi-cellular organism.

(ii) Locomotion is the ultimate criteria for classifying living organisms as plants and animals because animals have the ability to move while plants cannot move. However, there are other criteria for classification as well, e.g., presence of cell wall and chloroplasts in plants and their absence from animals.

Question 9 ( 5.0 marks)

Answer the following questions.

(i) Explain the basis of division of living organisms into five kingdoms.

(ii) Write a short note on bryophytes.

Solution:

(i) Organisms are divided into five kingdoms as follows:

(a) The first criteria kept in mind for classification is whether the organism is prokaryote or eukaryote. All prokaryotes are kept in a separate kingdommonera.
(b) The eukaryotes can be unicellular or multicellular. All unicellular eukaryotes are kept in kingdom protista.
(c) The multicellular eukaryotes can be with a cell wall (kingdom fungi and kingdom plantae) or without a cell wall (kingdom animalia).
(d) In this way, we obtain the 5-kingdom classification of living organisms.
(ii) Bryophytes:
(a) Bryophytes are the plants whose body is differentiated into stems and leaves.
(b) Rhizoids are present instead of true roots.
(c) They lack specialised vascular tissue for the conduction of water.

(d) Naked embryos called spores are produced as a result of fertilisation.

Question 10 ( 5.0 marks)

(i) Complete the table.

-	Phylum/ Division	-	Main Characteristic
(a)	_________	(a)	Pseudocoelom present
(b)	Protochordate	(b)	Notochord only in ______ stage
(c)	________	(c)	Spiny covering made up of calcium carbonate
(d)	Arthropoda	(d)	_______ appendages
(e)	_________	(e)	Radial symmetry
(f)	_________	(f)	Dorsiventrally flattened bodies

(ii) Name the classes of subphyla vertebrata. How are these classes different in their respiratory and circulatory systems?

Solution:

(i)

-	Phylum/ Division	-	Main Characteristic
(a)	Nemathelminthes	(a)	Pseudocoelom present
(b)	Protochordate	(b)	Notochord only in embryo stage
(c)	Echinodermata	(c)	Spiny covering made up of calcium carbonate
(d)	Arthropoda	(d)	Joint appendages
(e)	Coelenterata	(e)	Radial symmetry
(f)	Platyhelminthes	(f)	Dorsiventrally flattened bodies

(ii) Classes of subphyla vertebrata:
(a) Pisces
(b) Amphibia
(c) Reptilia
(d) Aves
(e) Mammalia

Class	Pisces	Amphibia	Reptilia	Aves	Mammalia
Respiratory organ(s)	Gills	Gils in larval stage; lungs in adult stage	Lungs	Lungs	Lungs
Circulatory organ (Heart)	Two chambered	Three chambered	Three chambered	Four chambered	Four chambered