(a) Ureters in frogs: A ureter acts as a urinogenital duct, which carries sperms along with urine in male frogs.
(b) Malphigian tubules: Malphigian tubules are excretory organs in cockroaches.
(c) Body wall in earthworms: In earthworms, the body wall consists of muscle layers. It helps in movement and burrowing.
Which of the following is not correct?
(a) Robert Brown discovered the cell.
(b) Schleiden and Schwann formulated the cell theory.
(c) Virchow explained that cells are formed from pre-existing cells.
(d) A unicellular organism carries out its life activities within a single cell.
Describe the important steps in muscle contraction.
Name the components of the formed elements in the blood and mention one major function of each of them.
Bile juice contains no digestive enzymes, yet it is important for digestion. Why?
List the hormones secreted by the following:
(a) Hypothalamus
(b) Pituitary
(c) Thyroid
(d) Parathyroid
(e) Adrenal
(f) Pancreas
(g) Testis
(h) Ovary
(i) Thymus
(j) Atrium
(k) Kidney
(l) G-I Tract
Name two cell-organelles that are double membrane bound. What are the characteristics of these two organelles? State their functions and draw labelled diagrams of both.