STD 12 - 8. microbes in human welfare — NEET STD 11 Science — Question

Residual air is present in:

Mark the given statements True (T) or False (F).
(i) Sponges exhibit acellular level of organization while coelenterates exhibit tissue level of organization.
(ii) In open type of circulatory system the blood is pumped out of the heart and the cells and tissues are directly bathed in it.
(iii) When any plane passing through the central axis of the body divides the organism into identical halves, it is called radial symmetry and when only one plane can divide body into identical left and right halves, it is called bilateral symmetry.
(iv) Animals in which the cells are arranged in two embryonic layers, an external ectoderm and an internal endoderm, are called diploblastic animals.
(v) In triploblastic animals, the extra germinal layer present in middle is called mesoderm and members of phylum etenophora to chordates are triploblastic organisms.
(vi) The body cavity which is lined by mesoderm is called coelom and animals possessing that are called coelomates.
(vii) In pseudocoelomates the mesoderm is present as scattered pouches in between the ectoderm and endoderm.
(viii) The animals in which the body cavity is absent are called acoelomates.
(ix) The phenomenon in which the body of animal is divided only externally into segments with a serial repetition of at least some organs is known as metamerism.
(x) Notochord is mesodermally derived and rod- like structure formed on the ventral side during embryonic development in some animals.
(xi) Members of the phylum porifera are commonly known as sponges.
(xii) Sponges have water transport system which is called as canal system.
(xiii) In porifera, water enters through minute pores in the body wall into a central cavity. spongococl, from where it goes out through the ostia.
(xiv) Choanocytes or collar cells line the spongocoel and the canals.
(xv) The body of sponges is supported by a skeleton made up of spicules or spongin fibres.
(xvi) The fertilisation in porifera is internal and development is direct.
(xvii) In coelenterata, cnidoblast are used for anchorage, defence and for capture of prey.
Choose the correct option given below :-

In cockroach, nephrocytes are concerned with

Curding of milk takes place by

If excess water passes out from the tissue without being restored by the kidneys, the cells would

Which of the following is mainly produced by the activity of anaerobic bacteria on sewage?