New cells generate from
(a) bacterial fermentation (b) regeneration of old cells
(c) pre-existing cells (d) abiotic materials

Who first explain that cells divide and new cells are formed from pre-existing cells?

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.

Which of the following is correct: (a) Cells of all living organisms have a nucleus. (b) Both animal and plant cells have a well defined cell wall. (c) In prokaryotes, there are no membrane bound organelles. (d) Cells are formed de novo from abiotic materials.

Given below are types of cells present in some animals. Which of the following cells can differentiate to perform different fucntions ? (A) Choanocytes (B) Interstitial cells (C) Gastrodermal cells (D) Nematocytes

By which, Hydra conducts nerve impulse and stimulation ? (A) Nervenet (B) Nematocytes (C) Sensory cells (D) Nerve cells

In an embryo sac, the cells that degenerate after fertilisation are (A) Synergids and primary endosperm cell (B) Synergids and antipodals (C) Antipodals and primary endosperm cell (D) Egg and antipodals

In albuminous seed the food is stored in (A) testa (B) tegmen (C) aleurone cells (D) endosperm

New species may be formed if: ( 1 ) DNA undergoes significant changes in germ cells. (2) there is no change in the genetic material. (3)mating does not take place. a.(1) and (2) b.(1) c.( 2) and (3) d.(1 ), (2) and (3)

Choose the options which is having all true statements. (1) Sperm gets nutrition from sertoli cells (2) Sertoli cells produce androgens (3) Leydig cells produce androgrens (4) Leydig cells are produced by ovary. (5) Menstruation is not observed during pregnancy (A) 1, 3 and 5 (B) 3, 5 (C) 2, 4 and 5 (D) 3, 4 and 5

A dry cell of emf 1.5V and internal resistance 0.10 Omega is connected across a resistor in series with a very low resistance ammeter: When the circuit is switched on, the ammter reading settles to a steady value of 2.0A. What is the steady (a) rate of chemical energy consumption of the cell, (b) rate of energy dissipation inside the cell, (c) rate of energy dissipation inside the resistor, (d) power output of the source?