Chapter 11 - CELLS IN MULTICELLULAR ORGANISMS

The unicellular paramecium shape

is shaped like a football and covered in cilia.

paramecium movement

The movements of the cilia are synchronised, enabling the organism to move through the water

paramecium special feature apart from other protists

One feature that sets paramecium apart from some other protists is that it gathers its organic nutrient requirements, such as bacteria, algae and yeasts, from its surroundings. By using its cilia, it sweeps food, along with some water, into its oral groove and then into the mouth of the cell.

paramecium food travel

The food travels through the cell mouth into the gullet, which is a temporary holding area for the food.

paramecium food

When there is enough food in the gullet, the food breaks away and forms a food vacuole.

paramecium waste

Expulsion of wastes from the food vacuole occurs through an anal pore.

paramecium expelling

Throughout this process, the vacuole is making its way to the back end of the cell. The paramecium collects the excess water that enters the cell with the food in a contractile vacuole and expels it from the vacuole back into the environment.

different types of tissue

In a vascular plant, there are four main types of plant tissues:

meristematic, dermal, ground and vascular. These tissues perform specialised functions such as storage, transportation, photosynthesis and growth.

Explain Why cells in a multicellular organism cannot survive independently of other cells

Cells in multicellular organisms are specialised. They have specific structures and functions.

They are totally dependent on other cells to perform tasks that they cannot.

Distinguish between specialisation and differentiation

Cells become specialised (or different) through cellular differentiation. Specialisation is when

the different cells possess specific features that relate to a specific role or function.

If all cells of a multicellular organism contain the same genetic material, explain why they dont look the same

Only a small portion of the genetic material is actively ‘switched on’ in specialised cells. The

specific genes that are ‘switched on’ and expressed will determine the cell’s structure.

Disadvantage and Advantage of of specialised cells on the survival of organisms

The possession of specialised cells is advantageous to the survival of the organism because

cells are able to perform many more processes due to their more complex structures.

The possession of specialised cells is disadvantageous to the survival of the organism

because cells are so specialised that they cannot exist independently of other cells, so the

organism must spend energy on communication and coordination between cells.

Describe the differences in the structures involved in systematic and pulmonary circulation

During systemic circulation, arteries carry blood from the heart and veins carry blood to the

heart. The blood flow for pulmonary circulation is reversed; pulmonary arteries carry blood to

the heart and pulmonary veins carry blood from the heart

The fibrous nature of valves allows blood to push the flaps open, when being pushed by

muscular contractions of blood vessels or the heart, but prevents blood flowing backwards

The fibrous nature of valves allows blood to push the flaps open, when being pushed by

muscular contractions of blood vessels or the heart, but prevents blood flowing backwards