Biology Grade 6 - Chapter 1: The Cell

A collection of practice questions and answers covering the first chapter of grade 6 biology on cell structure, types, organelles, and division.

Who was the first scientist to see the cell?

German scientist Antoine Van Leeuwenhoek (1632-1723)

How did Robert Hooke define the cell?

Hooke defined the cell as an aerobic chamber similar to a bee hive.

What was the contribution of Robert Brown in 1831?

He discovered and described the nucleus of the cell.

Which two scientists are credited with formulating the cell theory?

Mathias Schleidein (1838) and Theodor Schwann (1839)

What are the three main tenets of the Cell Theory?

a. All organisms are made of cell or cells. b. Cells are the basic structural and functional units of all organisms. c. The cell is produced from another cell by means of cell division.

What is the diameter of a frog's egg?

$$1\,mm$$

What is the size of a human egg?

$100\,\mu m$ or less.

What is the 'nuclear zone' or 'nucleoid' in a prokaryotic cell?

It is the genetic material in a prokaryotic cell that exists without a surrounding membrane.

Name the chemical compounds that make up the bacterial cell wall.

Protein, lipids, and polysaccharides.

Which organisms belong to the kingdom Monera?

Blue green algae, bacteria, and Mycoplasma.

What is the 'Dictyosome'?

It is the name given to the Golgi apparatus in a plant cell, where it builds cellulose and some components of the cell wall.

What are the three layers of the plant cell wall?

Middle Lamella, Primary Wall, and Secondary Wall.

Which organelle is known as the 'Energy house' and why?

Mitochondria, because they are involved in producing high-energy Adenosine tri-phosphate ($ATP$).

What are 'Cristae' and what is their function?

Curves and folds in the inner layer of the mitochondria that increase the surface area of the inner layer for respiratory enzymes.

Identify the three types of plastids and their functions.

a. Chromoplasts (contain pigments for flower/fruit color). b. Leucoplasts (convert glucose into starch, fats, or proteins). c. Chloroplasts (contribute to photosynthesis).

Define 'Autolysis' in the context of lysosomes.

A process where lysosomes release enzymes into the cytoplasm, digesting the cell's contents and leading to cell death, often occurring during metamorphosis or after an organism's death.

What proteins are contained in microfilaments responsible for cell expansion and contraction?

Actin and myosin.

What is the 'Kinetosome' (basal body)?

A structure located at the base of the cilium or flagellum that plays a vital role in their movement.

How many chromosomes are found in a human somatic cell?

$46$ chromosomes.

What is the chromosome count in the Spanish butterfly?

$380$ chromosomes.

Define 'Diffusion'.

Movement of ions and particles in a certain medium from high concentration regions to low concentration regions.

What is 'Active Transport'?

The process where cells absorb materials from the outside against a concentration gradient using carriers in the cell membrane and energy supplied by $ATP$.

What is the difference between phagocytosis and pinocytosis?

Phagocytosis is 'cellular eating' of solid matter, while pinocytosis is the intake of liquid material into vesicles.

How much total energy ($ATP$) is released from oxidizing one-gram molecule of glucose during aerobic respiration?

$$38\,ATP$$

Name the five stages of Prophase 1 in Meiosis.

Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis.

What occurs during the 'Zygotene' stage?

Homologous chromosomes align, double, and bend on each other in a process called Synapsis, forming a bivalent.

What is 'Crossing Over' during the Pachytene stage?

An exchange of gene locations between identical (homologous) chromosomes.

What are 'Chiasmata'?

The connection points where non-sister chromatids remain attached during the Diplotene stage of meiosis.

Contrast cytokinesis in animal and plant cells.

In animal cells, the cell membrane constricts (furrows) from the outside inward. In plant cells, a cell plate is formed at the equator by the cell protoplasm, growing from the center outward.