Which statement about the cell membrane is true? it contains cellulose and sugars that are involved in communication. it is present in animal cells only. it is rigid and elastic for supporting the cell’s shape. it prevents harmful substances from entering a cell.

The right answer is It prevents harmful substances from entering a cell.

The cell membrane is the membrane that delimits a cell.

• it separates unicellular organisms from their aqueous external environment and cells from multicellular organisms from extracellular fluid

• selective and dynamic to facilitate or prevent the entry and exit of harmful substances.

The correct answer is option D

Explanation: The cell membrane acts as a protective covering and prevents the harmful  substances from entering into the cell.

The cell membrane is selectively permeable, it allows only some substances to pass through it. For a membrane to be selectively permeable it means some substances can pass through it freely but others cannot.

So, by allowing only materials that is useful and preventing other materials from entering makes it selectively permeable.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.