SS1 First Term Biology Lesson Note – Cell and Its Environment and Some Properties and Functions of Cells

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WEEK 5

SUBJECT: BIOLOGY

CLASS: SS1

TOPIC: Cell and its Environment and some properties and functions of cells                                                         

CONTENT: 

(1) Diffusion

(2) Osmosis

(3) Plant nutrition

(4) Micro and Macro Nutrient

The topic ‘Cell and its Environment’ refers to the activities of the cell in a given environment or the functions of the cell given a particular condition. Some conditions can be harmful to the cell while others are helpful for proper functioning of the cell. This is why we discuss the cell and its environment.

diffusion

Diffusion can take place in liquid and gases, but diffusion is faster in gases than in liquid, because air and gases as a medium has more spaces to be filled.

Diffusion can be defined as the process by which molecules of substances, such as liquid and gases move randomly from a region of higher concentration to a region of lower concentration until they are evenly distributed.

It is also a process by which fine particles (molecules) flow in and out of cells of living things, and it can occur in non-living things or membrane.

SUGGESTED PRACTICALS

Stand at the corner of the classroom, and spray a perfume, after a while the scent of the perfume will circulate the whole class and every student will testify to the perception. This is diffusion in gas.

You can also demonstrate diffusion of solid material in liquid medium using potassium tetraoxomanganate (vii) crystals. i.e., KMnO₄

Materials: Distilled water, Beakers, Spatula, and KMnO₄.  

RATE OF DIFFUSION

The rate of diffusion is the time taken by molecules of a diffusing substance to be uniformly distributed in any given area of the diffusing medium.

Some factors may affect (inhibit or facilitate) the rate of diffusion:

1. State of matter of diffusing molecules
2. Size of diffusing molecules
3. Differences in concentration of diffusing molecules and the medium (conc. gradient).
4. Temperature of diffusing medium.

IMPORTANCE OF DIFFUSION

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