The fundamental Unit of life Flashcards
Who first discovered cells and in what year?
Robert Hooke in 1665
Hooke observed cells in a cork slice using a self-designed microscope.
What does the term ‘cell’ mean in Latin?
A little room
The term ‘cell’ was used by Hooke to describe the compartments he observed.
What is the cell theory?
All plants and animals are composed of cells, and the cell is the basic unit of life
Proposed by Schleiden and Schwann in 1838-1839 and expanded by Virchow in 1855.
What are unicellular organisms?
Organisms made up of a single cell
Examples include Chlamydomonas, Paramecium, and bacteria.
What is the basic unit of life?
Cell
Cells perform all basic functions necessary for living organisms.
What is the plasma membrane?
The outermost covering of the cell that separates its contents from the external environment
It is selectively permeable, allowing certain materials to enter or exit.
What is diffusion?
The spontaneous movement of a substance from a region of high concentration to a region of low concentration
Important for gas exchange in cells.
What is osmosis?
The net diffusion of water across a selectively permeable membrane toward a higher solute concentration
Affects the movement of water in and out of cells.
What happens to a cell in a hypotonic solution?
The cell gains water and may swell
Occurs because the outside solution has a higher water concentration than the cell.
What happens to a cell in an isotonic solution?
There is no net movement of water across the cell membrane
The cell remains the same size.
What happens to a cell in a hypertonic solution?
The cell loses water and may shrink
The outside solution has a lower concentration of water than the cell.
What is plasmolysis?
The shrinkage or contraction of the cell contents away from the cell wall due to water loss
Observed in living plant cells when they lose water.
What is the role of cell organelles?
Perform specific functions within the cell
Examples include making new materials and clearing waste.
What is the cell wall made of?
Cellulose
Provides structural strength to plant cells.
What is the function of the nucleus in a cell?
Control center of the cell, containing genetic material
Discovered by Robert Brown in 1831.
Fill in the blank: The process by which Amoeba acquires food is called _______.
Endocytosis
A process that allows cells to engulf food and substances.
What is the significance of magnifying lenses in biology?
Led to the discovery of the microscopic world
Enabled scientists to observe cells and their structures.
True or False: All cells have the same organelles regardless of their function.
True
All cells are found to have similar organelles.
What is the main difference between unicellular and multicellular organisms?
Unicellular organisms consist of a single cell, while multicellular organisms are made up of many cells
Multicellular organisms have specialized cells for different functions.
What are the three main features found in almost every cell?
- Plasma membrane
- Nucleus
- Cytoplasm
These features are essential for cell function and interaction with the environment.
What occurs when a living plant cell is placed in a hypotonic solution?
It swells due to water intake
The cell wall prevents it from bursting.
What is the function of chloroplasts?
Contain chlorophyll for photosynthesis
Found in plant cells, responsible for converting light energy into chemical energy.
What happens to a cell when it is placed in a concentrated salt solution?
The cell shrinks due to loss of water
Water moves out of the cell by osmosis.
What is the process of observing cells from our own body using a slide and methylene blue solution?
Taking a glass slide with a drop of water, scraping the inside surface of the cheek, and coloring the material with methylene blue for microscopic observation.
What is the structure called that is located near the center of each cell?
Nucleus
What is the function of the nuclear membrane?
It has pores that allow the transfer of material between the nucleus and the cytoplasm.
What do chromosomes contain?
Information for inheritance in the form of DNA molecules.
What are the functional segments of DNA called?
Genes
What is chromatin material?
Entangled mass of thread-like structures visible when the cell is not dividing.
What role does the nucleus play in cellular reproduction?
It directs the chemical activities of the cell and determines cell development.
What are prokaryotes?
Organisms whose cells lack a nuclear membrane.
What are eukaryotes?
Organisms with cells having a nuclear membrane.
What does the cytoplasm contain?
Fluid content and specialized cell organelles.
What is the endoplasmic reticulum (ER)?
A large network of membrane-bound tubes and sheets.
What are the two types of endoplasmic reticulum?
- Rough endoplasmic reticulum (RER) * Smooth endoplasmic reticulum (SER)
What is the primary function of the rough endoplasmic reticulum (RER)?
Sites of protein manufacture.
What is the primary function of the smooth endoplasmic reticulum (SER)?
Manufacture of fat molecules (lipids).
What is the function of the Golgi apparatus?
Storage, modification, and packaging of substances in vesicles.
What are lysosomes known as and why?
Suicide bags because they can digest their own cell when damaged.
What is the primary function of mitochondria?
Energy production in the form of ATP.
What are plastids and where are they found?
Organelles found only in plant cells.
What are the two types of plastids?
- Chromoplasts * Leucoplasts
What is the function of chloroplasts?
Photosynthesis in plants.
What do vacuoles store?
Solid or liquid contents.
What is the difference in size of vacuoles between plant and animal cells?
Vacuoles are small in animal cells and large in plant cells.
What is the fundamental organizational unit of life?
Cell
What are the two main types of cell division?
- Mitosis * Meiosis
What happens during mitosis?
A mother cell divides to form two identical daughter cells.
What is the main purpose of meiosis?
To form gametes with half the number of chromosomes.
What does the cell membrane regulate?
The movement of materials between the cell and the outer environment.
What are the components of the cell wall in plant cells?
Mainly cellulose.
What is the role of the central vacuole in plant cells?
To maintain turgidity and store important substances.
How do prokaryotic cells differ from eukaryotic cells?
- No membrane-bound organelles * Chromosomes composed of only nucleic acid * Smaller ribosomes
What happens if the plasma membrane ruptures?
The cell contents would leak out, leading to cell death.
Where are proteins synthesized inside the cell?
In ribosomes.
What is osmosis?
The movement of water across a semi-permeable membrane.
How is a prokaryotic cell different from a eukaryotic cell?
Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both.
What would happen if the plasma membrane ruptures or breaks down?
The cell would lose its integrity and essential substances, leading to cell death.
What would happen to the life of a cell if there was no Golgi apparatus?
The cell would be unable to properly modify, sort, and package proteins and lipids.
Which organelle is known as the powerhouse of the cell? Why?
Mitochondria are known as the powerhouse of the cell because they produce ATP through cellular respiration.
Where do the lipids and proteins constituting the cell membrane get synthesised?
Lipids are synthesized in the smooth endoplasmic reticulum, and proteins are synthesized in the rough endoplasmic reticulum.
How does an Amoeba obtain its food?
An Amoeba obtains its food through phagocytosis, engulfing food particles.
What is osmosis?
Osmosis is the movement of water molecules across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration.
Fill in the blank: The experiment involves four potato cups, one of which is made from a _______.
boiled potato
Explain why water gathers in the hollowed portion of B and C.
Water gathers in B and C due to the higher solute concentration (sugar and salt) outside the potato, causing water to move in.
Why is potato A necessary for this experiment?
Potato A serves as a control to show the effects of solute concentration on osmosis.
Explain why water does not gather in the hollowed out portions of A and D.
Water does not gather in A because it has no solutes; in D, the boiled potato’s cell structure is damaged, preventing osmosis.
Which type of cell division is required for growth and repair of the body?
Mitosis is required for growth and repair.
Which type of cell division is involved in the formation of gametes?
Meiosis is involved in the formation of gametes.
