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27

Match the following.

Animals Locomotory Organ
A. Octopus 1. Limbs
B. Crocodile 2. Comb plates
C. Catta 3. Tentacles
D. Ctenoplana 4. Fins

Explanation

A. $\rightarrow$ (iii) B. $\rightarrow$ (i) C. $\rightarrow$ (iv) D. $\rightarrow$ (ii)

(a) Octopus Tentacles are the appendages in invertebrates that are used for grasping food and for locomotion.

(c) Catta Fins Fins are means of locomotion and are used to generate optimum thrust thus controlling the subsequent motion.

(d) Ctenoplana Comb plates are locomotory organs formed by strong cilia with fused bases.

28

Differentiate between

(a) Open circulatory system and closed circulatary system.

(b) Oviparous and viviparous characteristic .

(c) Direct development and Indirect development.

Explanation

Differentiation between these are as below

(a) Open Circulatory System Closed Circulatory System
In this type of circulation, blood flows in spaces called sinuses and the cells and tissues are directly bathed in it.
e.g., arthropods (grasshopper, cockroach), gastropods (snail).
In this type of circulation, blood is circulated via a series of vessels (arteries, veins and capillaries).
e.g., annelids (earthworm) and vertebrates (birds, primates etc).
(b) Oviparous characteristics Animals Viviparous Characteristic Animals
Oviparity is expulsion of undeveloped eggs rather than live young ones
Animals that lay eggs. are called oviparous.
e.g., fishes, reptiles, amphibians, birds, in sects and monotremes (mammals that lay eggs).
Viviparity is retention and growth of fertilised egg within the material body until the young one is capable of independent existence.
Animals which give birth to their young ones and are called viviparous animals. e.g., mammals.
(c) Direct Development Indirect Development
Direct development is the type of development in which there is no larval/nymphal or other intermediate stages in life, cycle between the egg (or birth) and the adult (e.g., mammals) Indirect development is mostly observed in lower animals. The adult individuals lay eggs, which develop passing into the adult after passing through few to several larval nymphal stages. (e.g., echinoderms, arthropods)

29
Sort out the animals on the basis of their symmetry (radial or bilateral) coelenterates, ctenophores, annelids, arthropods and echinoderms.
Explanation

Body symmetry is the similarity of body parts in different region and directions of the body plan.

In radial symmetry, body of an individual can be divided into equal halves by any plans passing through the longitudinal axis. (e.g., Coelentrates, Ctenophores, Echinoderms.

In bilateral symmetry, body can be divided into two equal halves when the plane passes through the median longitudnal or saggital axis. (e.g., Annelids, Arthropods)

30
There has been an increase in the number of chambers in heart during evolution of vertebrates. Give the names of the class of vertebrates having two, three or four chambered heart.
Explanation

(a) Two chambered heart is present in organisms like fishes. Only one atria and one ventricle is present which are not separated and hence mixing of oxygenated and deoxygenated blood blood occurs.

(b) Three chambered heart develops after the division of auricle into right and left halves as in amphibian. Mixing of oxygenated and deoxygenated blood occurs in ventricles.

(c) An intermidiary heart is present in reptiles in which ventricle get partially divided through a septum which is incomplete. e.g., Crocodiles, thus having four-chambered heart.

(d) In four chambered heart both the auricle and ventricle are divided into two halves and thus no mixing of oxgyenated and deoxygenated blood occurs. e.g., birds and mammals.

31

Fill up the blank spaces appropriately

Phylum/Class Excretory Organ Circulatory Organ Respiratory Organ
Arthropoda Lungs/Gills/Tracheal System
Nephridia Closed Skin/Parapodia
Metanephridia Open
Amphibia Closed Lung

Explanation

Excretion involves the elimination of metabolic waste products from the animal body.

Different organs are involved in the process of excretion in different animals.

(a) In Arthropods, the Malpighian tubules remove excretory products from haemolymph.

(b) In Annelids, the excretory organ occurs as segmentally arranged coiled tubules called nephridia

(c) In Molluscas, excretion occurs by paired structures called organ of Bojanus also called metanephridia.

(d) In Amphibians mesonephric kidneys are associated with excretion.

Blood circulation involves the circulation of blood and lymph along with oxygen, carbondioxide, hormones, blood cells, etc, within the body system for the nourishment of cells, fighting diseases, and for stabilising body temperature and pH .

Open Circulation Closed Circulation
In this, blood is pumped out of the heart into sinuses which directly open into cells and tissues, e.g., phylum-Arthropoda, and Mollusca. In this system, blood is circulated through a series of complexly arranged vessels and capillaries e.g., phylum-Annelida and Class-Amphibia.

Respiratory organs are involved in the exchange of gases from the atmosphere. Different respiratory organs are as follows

(a) Lungs/gills/tracheal system in arthropoda and molluscs.

(b) Skin in annelids.

(c) Lungs and skin in amphibians.