Class 9 Science : Practice Questions and Answers

Plant cell walls are mainly composed of cellulose, which provides support and protection.

The plasma membrane is semi-permeable and regulates the movement of substances into and out of the cell.

Mitochondria produce ATP, which supplies energy for cellular activities.

Chloroplasts contain chlorophyll and carry out photosynthesis in plants.

Prokaryotic cells are generally very small and range from 0.1 to 5 micrometers in size.

The nucleus contains genetic material and controls cellular activities.

Bacteria are prokaryotes because they lack a true nucleus and membrane-bound organelles.

Hydra is a multicellular organism, whereas Amoeba, Paramecium, and Euglena are unicellular organisms.

The cell is the fundamental unit of life and performs all essential functions such as growth, metabolism, and reproduction.