Pollution of Water
A. Fill in the blanks.
B. Match the following column:
C. Tick the correct option.
Answer: a single cell
Answer: nuclear membrane
Answer: cell wall
Answer: cell → tissue → organ → organ system
D. Answer the following questions in brief.
Answer: The (main) factors that determine the shape of a cell are location and function.
Answer: Distinguish between unicellular and multicellular organisms are
Unicellular organisms are made up of a single cell. e.g., Euglena and Amoeba.
Multicellular organisms are made up of many cells. e.g., Humans and Birds.
Answer: All organisms are made up of cells. A cell is capable of independent existence. Due to this, cell is called the structural and functional unit of life.
Answer: Mitochondria is known as the Powerhouse of the cell.
Mitochondria are the site of cellular respiration. Energy is produced during this process. Due to this, mitochondria are called the Powerhouse of the cell.
Answer: Chloroplast is responsible for imparting colour to the leaves. Chromoplast is responsible for imparting colour to fruits.
E. Answer the following questions.
Answer: three different cell types found in human beings are:
These figures clearly show that liver cell is irregular in shape, fat cell is spherical and muscle cell is spindle-shaped. This shows that all cells in an organism do not have the same shape.
Answer: Chromosomes are formed in the nucleus during cell division. When the cell is ready to divide, the chromatin (in nucleus) condenses to form thicker, thread-like chromosomes. Chromosomes are responsible for inheritance of characters from one generation to the next generation.
Answer: three differences between a plant cell and an animal cell are:
|Plant Cell||Animal cell|
|Cell wall is present||Cell wall is absent|
|Chloroplast is present||Chloroplast is absent|
|Vacuole a very large||Vacuoles are small|
(a) Endoplasmic Reticulum- It is a network of membranes. It provides channels for transport of materials in a cell.
(b) Golgi Complex- They are sac-like structures stacked one above the other. They are involved in the processing and packaging of materials produced by the cell.
(c) Nucleus- a specialised structure in the cells, bound by the nuclear membrane; responsible for controlling all cellular activities.
(d) Chromoplasts- They are responsible for imparting colour (other than green) to the different parts of the plant.
(e) Vacuoles- It appears as an empty space in the cytoplasm. It is generally large in plant cells. It stores excess of water and waste products.
(f) Mitochondria- These are rod-shaped or spherical structures. They are responsible for cellular respiration and for generation of energy for different activities of life.