Question 1

In mammals and birds, why it is necessary to separate oxygenated and deoxygenated blood?

Accepted Answer

The circulatory system in birds and mammals consists of oygenated and deoxydenated blood. However, they have a double circulation system where the oxygenated as well as deoxygenated blood remain separate. This is essential to maintain the body temperature efficiently over a wide range. As mammals and birds require to keep their body warm, they require a higher supply of oxygen. Thus, it is beneficial if the oxygenated blood remains separate as its mixing with deoxygenated blood can make the entire blood impure.

Question 2

All vertebrates are chordates but all chordates are not vertebrates. Justify the statement.

Accepted Answer

All chordates have a notochord. Chordates include Urochordates, Cephalochordates (both are called protochordates) and vertebrates. In vertebrates notochord is replaced by vertebral column (backbone), however vertebral column is not present in protochordates. Therefore, all vertebrates are chordates but all chordates are not vertebrates.

Question 3

Differentiate between chordates and non-chordates.

Accepted Answer

CHORDATES NON-CHORDATES1) Animal having a notocord or backbone in their body structure are called chordates.1) Animals without a notochord are called non-chordates.2) Central nervous system is hollow and dorsal.2) It is solid and ventral.3) Heart is ventrally placed.3) If present, it is on the dorsal side.4) Haemoglobin is present in the RBCs.4) If present, it is dissolved in the plasma.5) Post anal tail is present.5) It is absent in them.6) Pharyngeal gill slits is present at some stage of life.6) It is absent in them.

Question 4

"All vertebrates are chordates but all chordates are not vertebrates". Justify the statement.

Accepted Answer

The characteristic features of the phylum Chordata include the presence of a notochord and paired pharyngeal gill slits. In sub-phylum Vertebrata, the notochord present in embryos gets replaced by a cartilaginous or bony vertebral column in adults. But in cephelochordates, notochord persists throughout life as such and in urochordates, the notochord is present only in larval stages and absent in adults. Thus, it can be said that all vertebrates are chordates but all chordates are not vertebrates.

Question 5

Which of the following are correct?(i) Sponges : Cellular level of organisation(ii) Cnidaria : Tissue level of organisation(iii) Platyhelminthes : Organ level of organisation(iv) Annelids, Arthropods, Molluscs, Echinoderms and Chordates : Organ system level of organisation.

Accepted Answer

Animals show four different grades of organization:(i) Protoplasmic grade found in protozoans.(ii)&#10; Cellular grade is the characteristic of sponges and mesozoans because &#10;in a sponge, cells exhibit division of labour for performing specialized&#10; functions.(iii) Tissue grade is of two types : Cell-tissue grade is&#10; seen in coelenterates as there are cells not only specialised for &#10;different functions but also certain similar cells gather together to &#10;form tissue as well. Tissue - organ grade appears in flatworms &#10;(Platyhelminthes) with arrangement of tissues to form organs.(iv) In&#10; organ system level of organisation, organs are joined in a system to &#10;perform basic functions. It is found in higher invertebrates and all &#10;vertebrates.Hence the correct option is D.

Question 6

Which of the following is not a character of the phylum Chordata?

Accepted Answer

Animals that belong to phylum Chordata are characterized by the presence of a notochord, a dorsal hollow nerve cord, and paired pharyngeal gill slits. These characters are known as three fundamental chordate characters. In some chordates notochord is replaced by the vertebral column in the adult stage. Protochordates i.e., Urochordata and Cephalochordata don't have a well-developed spinal cord. Thus, the correct answer is option D

Question 7

Tissue level of organization is found in:

Accepted Answer

Comb jelly belongs to the phylum Ctenophora and shows tissue level of organization. It does not show the presence of organs and organ systems. They are marine, radially symmetrical, and diploblastic organisms.Thus, the correct answer is option D.

Question 8

Which of the following has mesoderm but no coelom?

Accepted Answer

When the animal does not possess body cavity it is called acoelomate condition. The animals which are belonging to Platyhelminthes are acoelomate. They do not have body cavity. These are elongated and flattened worms. These are bilaterally symmetrical animals. The body organs and the parts are made up of the three germ layers called as the ectoderm, mesoderm, and endoderm.Thus, the correct answer is option A.

Question 9

Justify the statement Mammals are the most successful and dominant animals today.

Accepted Answer

Mammals are the most successful and dominant animals today. They thrive very well in most of the environment of the world. Unique mammalian characteristics are: (a) Body covered with hair.(b) Presence of sebaceous and sweat glands in the skin.(c) Presence of mammary glands in females.(d) The heart is four chambered.(e) The red blood corpuscles (erythrocytes) are biconcave and enucleated.(f) Corpus callosum unites two cerebral hemispheres.(g) Testes are extra-abdominal in scrotal sacs.(h) Presence of penis for copulation in males.(i) Mostly viviparous and embryo attached to the uterine wall by the placenta.

Question 10

Meena and Hari observed an animal in their garden. Hari called it an insect while Meena said it was an earthworm. Choose the character from the following which confirms that it is an insect.

Accepted Answer

Arthropoda is the largest phylum of animals within which, the class Insecta has the maximum number of species. Insects make up around 75% of the phylum Arthropoda. They occupy a variety of habitats and can crawly, fly, jump and swim.  The word arthropod has a Greek origin and is made up of two words, arthron meaning 'joint' and pous meaning 'foot'. Hence, insects are basically animals with jointed legs.So, the correct answer is 'Body with jointed legs'.