8. Cell – Structure and Functions
1. Indicate wether the following staements are True or False
(a) True
(b) False
(c) False
(d) True
2. Draw the diagram of nerve cell:
Function of nerve cell: To transfer nerve impulses from one end to the other.
3. Write short notes:
(1) Cytoplasm: It is the jelly like substance present between the cell membrane and the nucleus.
Various other organelles of cells are present in it.
(2) Nucleus: It is an important component of a cell. It is located in the centre of the cell. Nucleus
is separated from the cytoplasm by a membrane called the nuclear membrane. Nucleus contain a
smaller spherical body called nucleolus and thread like structures called chromosomes.
4. Cytoplasm
5. Draw the diagram given in figure 8.7 of the textbook on page96.
Comparison of plant and animal cell:
S.No. Feature
Plant cell
Animal cell
1.
Cell wall
Present
Absent
2.
Chloroplast
Present
Absent
3.
Vacuole
Large in size
Small in size
6.
S.No.
1.
2.
Eukaryotes
Nucleus is well organized with well-defined
nuclear membrane.
Eg. Onion cell, cheek cell.
Prokaryotes
Nucleus is not well organized and nuclear
membrane is not present.
Eg. Bacteria, Blue-green algae.
7. Nucleus contains thread like structures called chromosomes. These carry genes and help in
inheritance or transfer of genetic information from the parents to the offspring.
8. Cells are the basic structural and functional units of life: Cells make up the smallest level of a living
organism such as yourself and other living things. The cellular level of an organism is where the
metabolic processes occur that keep the organism alive. That is why the cell is called the fundamental
unit of life.
9. Green coloured plastids are called chloroplast and they contain green coloured pigment called
chlorophyll which is essential for photosynthesis.
10. Across:
1. Chlorophyll 2. Organelle
6. Protoplasm 8. Genes
Down:
1. Chloroplast 2. Organ
4. Membrane 5. Vacuole
7. Tissue