Organisation des êtres vivants Practice Quiz (9 questions)

1. What distinguishes a multicellular organism from a unicellular organism?

A. It contains several specialised cells that perform different functions.

B. It contains tissues that perform all functions within one cell.

C. It contains one cell that performs all functions needed for life.

D. It develops from several unrelated cells with identical functions.

Answer: (A)

Explanation

A multicellular organism is made of several specialised cells whose different functions support the organism. The most plausible alternative describes a unicellular organism, in which one cell carries out all necessary life functions.

2. Which sequence correctly represents the organisational hierarchy from simplest to most complex?

A. Tissue → Cell → Organism → Organ

B. Cell → Tissue → Organ → Organism

C. Cell → Organ → Tissue → Organism

D. Organism → Organ → Tissue → Cell

Answer: (B)

Explanation

The hierarchy progresses from individual cells to groups of similar cells called tissues, then organs, and finally the complete organism. Placing organs before tissues reverses the normal level of organisation.

3. What genetic feature do cells of the same organism initially share?

A. They inherit DNA from several unrelated egg cells.

B. They begin with different genes activated in each cell.

C. They possess the same DNA inherited from one egg cell.

D. They contain different DNA suited to their future functions.

Answer: (C)

Explanation

Cells in the same organism originate from one egg cell and initially carry the same genetic information. Their later functional differences are not caused by starting with different DNA.

4. How can cells with the same DNA become specialised for different functions?

A. Cells acquire different chromosomes from neighbouring tissues.

B. Each cell replaces its original DNA with specialised DNA.

C. The entire genome becomes active in every cell at once.

D. Different genes become expressed in different cells.

Answer: (D)

Explanation

Different patterns of gene expression cause cells that share the same DNA to develop distinct structures and functions. Replacing the original DNA is not the mechanism of cellular specialisation.

5. What does cellular specialisation allow cells with the same DNA to do?

A. Change their DNA sequence to suit functions.

B. Perform different functions through different gene expression.

C. Remain undifferentiated and perform the same role.

D. Share identical functions across all cell types.

Answer: (B)

Explanation

Cellular specialisation enables cells with identical DNA to perform different functions by activating specific genes. Changing DNA sequences is not part of this process, and undifferentiated cells do not perform specialised roles.

6. Which bases in DNA form complementary pairs, with adenine pairing with thymine and guanine pairing with cytosine?

A. Adenine pairs with cytosine, and guanine pairs with thymine.

B. Adenine pairs with guanine, and thymine pairs with cytosine.

C. Adenine pairs with uracil, and guanine pairs with cytosine.

D. Adenine pairs with thymine, and guanine pairs with cytosine.

Answer: (D)

Explanation

In DNA, adenine (A) pairs specifically with thymine (T), and guanine (G) pairs specifically with cytosine (C). This pairing is fundamental to the structure of the DNA double helix.

7. What is the primary role of the extracellular matrix in tissues?

A. It maintains cohesion between cells and contributes to tissue formation.

B. It enables the production of energy usable by the cell.

C. It contains genetic information for the cell.

D. It stores waste products and various substances in cells.

Answer: (A)

Explanation

The extracellular matrix mainly functions to maintain cohesion between cells and support tissue structure. Unlike mitochondria, which produce energy, or the nucleus, which stores genetic information, the extracellular matrix provides structural support and tissue integrity.

8. How do unicellular and multicellular organisms differ in their organizational complexity?

A. Unicellular organisms are always larger than multicellular organisms.

B. Multicellular organisms do not have specialised cells, unlike unicellular organisms.

C. Unicellular organisms have multiple cells with specialised functions, whereas multicellular organisms are made of a single cell.

D. Unicellular organisms consist of one cell performing all functions, while multicellular organisms have multiple specialised cells performing different functions.

Answer: (D)

Explanation

Unicellular organisms are made up of a single cell that performs all necessary functions, whereas multicellular organisms contain many specialised cells that perform different functions, increasing organizational complexity.

9. What is a primary consequence of cellular specialisation in multicellular organisms?

A. All cells in an organism perform the same functions regardless of gene activity.

B. Cells with the same DNA can perform different functions due to gene expression.

C. Cells with different DNA can perform similar functions.

D. Cellular specialisation leads to the loss of genetic information in some cells.

Answer: (B)

Explanation

Cellular specialisation allows cells with identical DNA to perform different functions through selective gene expression. The other options are incorrect because they either suggest DNA differences where there are none or imply that all cells perform the same function, which contradicts the concept of specialisation.