How do substances like CO 2 and water move in and out of the cell? Discuss.

The molecules, in general, tend to move from a place of their higher concentration to a lower concentration. This process is known as diffusion. The diffusion of water across a semi-permeable membrane is called osmosis. It can be observed between the cytoplasm of cells and extracellular fluid. The molecules such as CO 2 and water move across a cell with respect to their concentration gradient. If the concentration of CO 2 and water molecules is high within the cytoplasm of a cell as compared to extracellular fluid, they move outside the cell and vice versa.

Fill in the gaps in the following table illustrating the differences between prokaryotic and eukaryotic cells. Prokaryotic cell Eukaryotic cell 1 . Size Generally small ( 1 - 10 μ m ) 1 μ m = 10 - 6 m Generally large ( 5 - 100 μ m ). 2 . Nuclear region _____ Well-defined and surrounded by a nuclear membrane. 3 . Chromosome Single More than one chromosome 4 . Cell organelles Membrane-bound cell organelles are absent. _____

Prokaryotic cell Eukaryotic cell Size Generally small ( 1 - 10 μ m ) 1 μ m = 10 - 6 m . Generally large ( 5 - 100 μ m ). Nuclear region In some organisms like bacteria, the nuclear region of the cell maybe poorly defined due to the absence of a nuclear membrane. Such an undefined nuclear region containing only nucleic acids is called nucleoid. Well-defined and surrounded by a nuclear membrane. Chromosome Single More than one chromosome. Cell organelles Membrane-bound cell organelles are absent. Membrane-bound cell organelles [e.g., chloroplasts(exclusively present in plants, algae, etc.), Golgi bodies, mitochondria, etc.] are present.

E M B I B E

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 5 - The Fundamental Unit of Life>Questions>Q 1

EASY

9th CBSE

IMPORTANT

Earn 100

Who discovered cells, and how?

Important Questions on The Fundamental Unit of Life

EASY

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 5 - The Fundamental Unit of Life>Questions>Q 2

Why is the cell called the structural and functional unit of life?

MEDIUM

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 5 - The Fundamental Unit of Life>Questions>Q 1

How do substances like CO₂ and water move in and out of the cell? Discuss.

EASY

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 5 - The Fundamental Unit of Life>Questions>Q 2

Why is the plasma membrane called a selectively permeable membrane?

MEDIUM

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 5 - The Fundamental Unit of Life>Questions>Q 1

Fill in the gaps in the following table illustrating the differences between prokaryotic and eukaryotic cells.

	Prokaryotic cell	Eukaryotic cell
$1 .$ Size	Generally small ( $1 - 10 μ m$ ) $1 μ m$ $= 10^{- 6} m$	Generally large ( $5 - 100 μ m$ ).
$2 .$ Nuclear region	_____	Well-defined and surrounded by a nuclear membrane.
$3 .$ Chromosome	Single	More than one chromosome
$4 .$ Cell organelles	Membrane-bound cell organelles are absent.	_____