Cell Envelope and Osmosis | The Fundamental Unit of Life | Assessment | English | Grade 9

Cell envelope is made up of ____ and ____.

• Cell wall and cytoplasm

• Cell wall and cell organelles

• Cell wall and nuclear membrane

• Cell wall and plasma membrane

Answer explanation

Cell envelope is made up of cell wall and plasma membrane or cell membrane.

Which of the following is not true for plasma membrane?

• It is the innermost layer of the animal cell

• It allows entry or exit of some materials in and out of the cell

• It is known as semi permeable membrane or selectively permeable membrane

• All of these

Answer explanation

Option 1 is incorrect. Plasma membrane is the outermost layer of the animal cell that separates content of the cell from external environment.

Tags

NGSS.MS-LS1-2

What is diffusion?

• Process in which solid, liquid or gaseous substances move from low concentration to high concentration

• Process in which solid, liquid and gaseous substances move from higher concentration to lower concentration

• Process in which only solid substances move from low concentration to high concentration

• Process in which only liquid substances move from low concentration to high concentration.

Answer explanation

Diffusion is the process in which solid, liquid and gaseous substances move from higher concentration to lower concentration.

Select the correct sentence with respect to osmosis.

• The process in which oxygen molecules move from higher concentration to lower concentration through a semipermeable membrane.

• The process in which carbon dioxide molecules move from higher concentration to lower concentration through a semipermeable membrane

• The process in which water molecules move from higher water concentration to lower water concentration through a semipermeable membrane.

• The process in which solute molecules move from lower concentration to higher concentration through a semipermeable membrane.

Answer explanation

The process in which water molecules move from higher water concentration to lower water concentration through a semipermeable membrane is called osmosis.

When a dried raisin is kept in water for some time, it

• swells

• shrinks

• remains same

• none of these

Answer explanation

Dried raisin when placed in water swells up. This is because dried raisin has lower water concentration and when placed in water, water concentration outside raisin becomes higher. Due to this osmosis takes places and water molecules moves from higher water concentration (from outside the raisin) to lower water concentration ( to inside the raisin), which causes raisin to swell.

Tags

NGSS.MS-LS1-5

Ritu placed some raisins in the sugar solution. What will happen to raisins?

• Raisins will swell

• Raisins will shrink

• Raisins will remain same

• none of these

Answer explanation

Sugar solution has lower water concentration. When raisins are placed in sugar solution. water molecules from raisins move from higher water concentration (from raisin) to lower water concentration (to sugar solution), and thus raisin shrinks.

Tags

NGSS.MS-LS1-5

NGSS.MS-PS1-2

If the medium surrounding the cell has higher water concentration than the cell, then the solution is known as ____ solution.

• hypotonic

• isotonic

• hypertonic

• none of these

Answer explanation

If the medium surrounding the cell has higher water concentration than the cell, then the solution is known as hypotonic solution.

Tags

NGSS.MS-LS2-1