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03. The Cell

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Prepared by: learnloophq@gmail.com
Last edited 25 days ago by Learn LoopHQ.

Chapter: 03. The Cell

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What is the primary definition of a cell?
A cell is the smallest fundamental unit of structure and function in all living organisms, carrying out all basic life processes.
Who discovered cells and when?
Cells were discovered by Robert Hooke in the year 1665.
What significant contribution did Robert Hooke make regarding the term ‘cell’?
Robert Hooke coined the term ‘Cell’ to describe the small, box-like structures he observed in cork.
List the two main statements of the Cell Theory.
The two main statements are that cells are the structural and functional units of living organisms, and new cells arise from the division of pre-existing cells.
How are unicellular organisms different from multicellular organisms in terms of cell number?
Unicellular organisms are composed of a single cell, while multicellular organisms are made up of many cells (millions or billions).
Give two examples of unicellular animals.
Two examples of unicellular animals are Amoeba and Paramecium.
Explain the concept of tissue formation in multicellular organisms.
In multicellular organisms, a tissue is formed when a group of similar cells specialized to perform a specific function come together.
Why do cells show variation in their shapes?
Cells show great variation in their shapes because their specific shape is closely related to the particular function they perform.
What is a key difference in shape between plant guard cells and animal muscle cells?
Plant guard cells are kidney-shaped or bean-shaped, whereas animal muscle cells are spindle-shaped with pointed ends.
What are pseudopodia and which animal cells are known for having them?
Pseudopodia are temporary, finger-like projections from the cell surface used for movement, and white blood cells (and Amoeba) are known for having them.
Which cell in the human body is considered the longest?
Nerve cells are considered the longest cells in the human body.
What is the approximate size of human Red Blood Cells (RBCs)?
Human Red Blood Cells (RBCs) are approximately 7.0 microns in size.
What are the three basic parts of a typical cell?
The three basic parts of a typical cell are the cell membrane, cytoplasm, and nucleus.
Why is the cell membrane called a selectively permeable membrane?
The cell membrane is called selectively permeable because it controls which substances, such as oxygen, water, and nutrients, are allowed to enter or leave the cell.
What is the main component of the plant cell wall?
The main component of the plant cell wall is cellulose.
What are the primary functions of the cell wall in plant cells?
The cell wall provides rigidity, mechanical support, and protection to the internal organelles of the plant cell.
What are chromatin fibres composed of and what is their significance?
Chromatin fibres are composed of deoxyribonucleic acid (DNA) and proteins; DNA is the hereditary material responsible for transmitting characteristics from parents to offspring.
Which human cells are unique for lacking a nucleus?
Mature Red Blood Cells (RBCs) in the human body are unique for being without a nucleus.
What is the role of the nucleolus within the nucleus?
The nucleolus is a rounded body within the nucleoplasm that contains ribonucleic acid (RNA) for the formation of ribosomes.
Where do many of the cell’s life processes take place within the cell?
Many of the cell’s life processes and chemical reactions take place within the cytoplasm.
Define protoplasm.
Protoplasm is the collective term for all the living matter of the cell, including the nucleus and cytoplasm, enclosed by the cell membrane.
Name the three types of plastids found in plant cells.
The three types of plastids found in plant cells are chloroplasts, chromoplasts, and leucoplasts.
What is the specific function of chloroplasts?
Chloroplasts carry out the process of photosynthesis, converting light energy into food due to the presence of chlorophyll.
What is the role of chromoplasts in plants?
Chromoplasts are responsible for giving various colors (red, yellow) to flowers and fruits.
What do leucoplasts store?
Leucoplasts are colorless plastids that store starch, proteins, and fats.
How does the vacuole in a mature plant cell differ from vacuoles in animal cells?
A mature plant cell typically has a single large central vacuole that maintains turgidity and stores substances, while animal cells either lack vacuoles or have only a few small, temporary ones.
List two functions of the vacuole in a plant cell.
Two functions of the vacuole in a plant cell are keeping the cell turgid (stiff) and storing water, food, and pigments.
Name two key structures present in a plant cell but absent in an animal cell.
Two key structures present in a plant cell but absent in an animal cell are the cell wall and plastids.
Name an organelle present in animal cells but absent in plant cells.
Centrioles are an organelle present in animal cells but absent in plant cells.
Why is cell division important for repairing tissues?
Cell division is important for repairing tissues because it produces new cells that can replace damaged or wounded cells, thus restoring the integrity of the tissue.
What is staining in the context of studying cells?
Staining is the process of coloring cells with a dye (stain) to differentiate and identify their various parts more clearly under a microscope.
Describe the general appearance of onion peel cells under a microscope.
Under a microscope, onion peel cells appear as brick-shaped cells arranged side-by-side, each with a distinct cell wall, a large vacuole, and a thin layer of cytoplasm.
How can you distinguish human cheek cells from onion peel cells based on their structure?
Human cheek cells are polygonal or irregular in shape and lack a cell wall and large central vacuole, whereas onion peel cells are brick-shaped and possess both a cell wall and a prominent central vacuole.
What is a distinguishing feature of Red Blood Cells (RBCs) observed under a microscope?
Red Blood Cells (RBCs) are distinguishable as concave cells without a nucleus when observed under a microscope.
Describe the main locomotive structures of Chlamydomonas.
Chlamydomonas possesses two flagella, which are whip-like structures primarily used for locomotion.
Describe the shapes of Xylem vessels and Mesophyll cells in plants.
Xylem vessels in plants are cylindrical cells, while mesophyll cells of leaves are long and rectangular, containing chloroplasts.
How are nerve cells structurally adapted for their function?
Nerve cells are quite long and branched at their ends, which enables them to transmit messages over long distances efficiently.
Why do larger organisms have more cells rather than bigger cells?
Larger organisms have more cells rather than bigger cells because increasing cell size beyond a certain point becomes inefficient for nutrient and waste exchange, while having more cells allows for greater specialization and complexity.
What is the function of the nuclear pores in the nuclear envelope?
The nuclear pores in the nuclear envelope regulate the movement of substances, such as RNA and proteins, in and out of the nucleus.
What is the primary function of the Endoplasmic Reticulum (ER)?
The Endoplasmic Reticulum (ER) forms a supporting framework within the cell and helps in the transport of substances within the cell.
What are the main functions of the Golgi complex?
The Golgi complex is primarily associated with the secretion and storage of substances within the cell.
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