Chapter 3 : The Cell - A Unit of Life - Frank Solutions for Class 9 Biology ICSE
Chapter 3 - The Cell - A Unit of Life Excercise 25
(i) All living organisms are composed of cell. Hence cell is the structural unit of living organisms.
(ii) All cells arise from pre-existing cells of the similar kind by cell division.
(iii) The chemical composition and metabolism of all cells is basically alike.
The two types of cells are:
(i) Prokaryotic cells - These cells lack a well-organised nucleus and membrane bound organelles. They are usually found in unicellular organisms, which are referred to as prokaryotes. Example of prokaryotes are bacteria and blue-green algae.
(ii) Eukaryotic cells - These cells possess a well-organised nucleus and membrane bound organelles. Organisms made up of eukaryotic cells are called eukaryotes. Examples of eukaryotes are plants and animals.
(ii) Endoplasmic reticulum
(iv) Golgi body
(Write any 5)
(a) Robert Hooke
(b) Virchow stated that new cells originate only from pre-existing cells (omnis cellula e cellula).
(c) Schleiden found that all plant cells have essentially similar structure.
(d) Schwann observed that all animal cells are basically similar and lack cell wall.
(c) Cell membrane
(b) Ribosomes - It is the site of protein synthesis.
(c) Cell membrane - It gives definite shape to the cell, protects the internal cell contents and allows entry and exit of specific substances into and out of the cell.
Chapter 3 - The Cell - A Unit of Life Excercise 26
(i) Chloroplast - Green coloured plastids (due to presence of chlorophyll)
(ii) Chromoplast- Coloured plastids (except green colour)
(iii) Leucoplast - Colourless plastids
The main functions of plastids are:
(i) Chloroplasts trap solar energy and use it to synthesize carbohydrates from carbon dioxide and water by the process of photosynthesis.
(ii) Chromoplasts attract insects and other animals to ensure pollination and dispersal of fruits.
(iii) Leucoplasts store starch, proteins or lipids in cell.
(Write any 2 functions)
SER - Smooth Endoplasmic Reticulum
RER - Rough Endoplasmic Reticulum
(d) Endoplasmic Reticulum
(b) Chromosomes are the hereditary material of the nucleus, concerned with the transmission of hereditary traits from parents to offspring.
(c) Endoplasmic Reticulum increases the surface area of the cytoplasm for different metabolic activities of the cell.
(a) The single-celled alga ______ measures 10 cm in length.
(b) DNA is abbreviated form of ______.
(c) Cell ______ was proposed by Schleiden and Schwann.
(d) The largest cell in the animal kingdom is that of ______ egg.
(e) ______ controls all the metabolic activities of the cell.
(b) Deoxyribonucleic acid
Power house of cells - Mitochondria
Help in formation of cell plate during cell division - Golgi complex
Site for photosynthesis - Chloroplast
Control tower of cell - Nucleus
Structure bearing genes - Chromosomes
b - Nucleus
c - Chromatin
d - Nuclear membrane
e - SER
f - Mitochondria
g - Golgi vesicles
h - Golgi complex
i - RER
j - Ribosomes
(a) Who studied the cell first?
(b) Who says that cell is the biological unit of body structure?
(c) Which is the longest human cell?
(d) Name the longest cell.
(e) Where is energy stored in a cell?
(f) Which is the smallest cell?
(g) What do you mean by prokaryotic cell?
(b) Schleiden and Schwann
(c) Nerve cell
(d) Fibres of ramie
(f) The cell of Mycoplasma laidlawii
(g) Cell lacking a well-organised nucleus and membrane bound organelles is called prokaryotic cell.
Chapter 3 - The Cell - A Unit of Life Excercise 27
b - Nucleolus
c - Mitochondria
d - Golgi apparatus
e - Chloroplast
f - cell membrane
g - cell membrane
h - ER
i - Microtubule
(i) Cell theory states
(a) all cells have nucleus.
(b) all cells are living.
(c) cell reproduces by mitosis and meiosis.
(d) cells are functional and structural unit of plants and animals.
(ii) Chromosomes are made up of
(a) DNA (b) RNA (c) protein (d) by all the above three
(iii) Organelles found in plants only are
(a) golgi body (b) mitochondria
(c) plastid (d) ribosome
(iv) A prokaryotic cell doesn't have
(a) nucleus membrane
(b) cell wall
(d) plasma membrane
(v) Mitochondria was first seen by
(a) Robert Hooke
(vi) The word cell was given by
(b) Robert Hooke
(d) Robert Brown
(vii) Cell was discovered by
(a) Robert Hooke
(ii) (a) DNA
(iii) (c) plastid
(iv) (a) nucleus membrane
(v) (b) Altman
(vi) (b) Robert Hooke
(vii) (a) Robert Hooke
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