What is the cell’s role in living organisms?
It is their basic structural and functional unit.
Which work did Robert Hooke use to describe cork cells?
Micrographia.
Which scientists formulated cell theory in 1838 and 1839?
M. J. Schleiden and T. Schwann.
What does cell theory say all living organisms are composed of?
Cells and cell products.
What mainly determines a cell’s shape?
The specific function it performs.
What is a unicellular organism?
An organism made of one cell that performs all life processes.
Which structures distinguish plant cells from animal cells?
Plant cells have a cell wall, plastids, and a well-developed vacuole; animal cells lack a cell wall and plastids.
What is the first step in preparing a temporary onion-peel mount?
Separate a thin peel from the concave side of an onion scale.
How does a large central vacuole affect an onion-peel cell’s nucleus?
It pushes the nucleus toward the periphery.
How should cheek cells be collected for a temporary mount?
Gently scrape the inner cheek lining with a clean toothpick, spatula, or ice-cream spoon.
What is the plasma membrane, also called the cell membrane or plasmalemma?
A flexible boundary enclosing every living cell’s contents.
What are the main components of the plasma membrane?
A phospholipid bilayer and proteins.
What does selective permeability allow the plasma membrane to regulate?
The passage of specific molecules.
What direction does active transport move substances relative to their concentration gradient?
Against the concentration gradient.
What direction does passive transport move substances relative to their concentration gradient?
Along the concentration gradient, from higher to lower concentration.
Does passive transport require energy?
No, it does not require energy.
What is diffusion?
The movement of substances from higher to lower concentration until they spread uniformly through a space.
What is osmosis?
The net diffusion of water across a permeable membrane toward higher solute concentration.
What does endosmosis describe?
Osmotic entry of water into a cell or system.
What is the basic structural unit of life?
The cell.
Where do an organism’s life functions reside?
In its cells.
What happens to a plant, fungal, or bacterial cell in a hypotonic medium?
It takes up water by osmosis and swells.
What materials form the cell walls of plants, bacteria and blue-green algae, and most fungi?
Cellulose in plants, peptidoglycan in bacteria and blue-green algae, and chitin in most fungi.
What three functions does the cell wall provide?
It protects and supports the cell and gives it a definite shape.
What is plasmolysis?
The shrinkage of a living plant cell’s contents away from its wall after water loss by osmosis.
What causes a plant cell’s protoplasm to separate from its wall in a hypertonic solution?
Water leaves the central vacuole by exosmosis.
What does the nucleus contain and control, according to Robert Brown (1831)?
It contains genetic information and controls cellular metabolism.
What are the four components of the nucleus?
The nuclear envelope, nucleoplasm, nucleolus, and chromatin threads.
What hereditary role does the nucleus perform?
It carries hereditary information between generations.
Where does genetic material lie in prokaryotes lacking a nuclear membrane?
Freely as a nucleoid.
What is the cytoplasm?
The fluid inside the plasma membrane but outside the nucleus, containing cytosol and organelles.
What does the Svedberg unit indicate for ribosomes?
The sedimentation coefficient, which indirectly reflects density and size.
What are ribosomes, and what do they synthesize?
The smallest membrane-less organelles, composed of RNA and proteins, that synthesize proteins.
Which Golgi face points toward the nucleus, and what is its shape?
The convex cis face.
What does the Golgi complex do to materials destined for cell secretion?
It modifies, stores, condenses, and packages them.
What is a lysosome?
A single-membrane-bound vesicle containing hydrolytic enzymes.
What materials do lysosomes digest to help keep cells clean?
Foreign materials and worn-out organelles.
Why are lysosomes called suicidal bags?
They may release enzymes that digest a damaged cell itself.
Which cells lack mitochondria?
Prokaryotic cells and mature mammalian red blood cells.
What genetic and protein-making components do mitochondria contain?
A small circular chromosome, some RNA, and 70S ribosomes.
Which cells did Anton Van Leeuwenhoek first observe in pond water?
Free-living cells.
Who discovered the nucleus in 1831?
Robert Brown.
Who coined “protoplasm” for living matter inside the cell?
J. E. Purkinje.
Who expanded cell theory in 1855 with “omnis cellula e cellula”?
Rudolf Virchow.
What is the diameter of a normal human cell?
20–30 μm.
Which animal cell is the largest isolated single cell?
The ostrich egg.
How large are bacteria, and how do viruses differ structurally?
Bacteria measure 3–5 μm; viruses are smaller and lack cellular structure.
What shape do nerve cells have?
They are elongated and branched.
Why can Amoeba and white blood cells change shape?
To move and engulf particles.
Which organisms are examples of unicellular organisms?
Bacteria, Amoeba, Paramecium, and Chlamydomonas.
Which structures are included in the basic structure of a cell?
The cell membrane, protoplasm, cytoplasm, nucleus, and cell organelles.
Which organelles belong to each membrane-based classification group?
Single-membranous: endoplasmic reticulum, Golgi body, lysosomes, and plastids; double-membranous: mitochondria; non-membranous: ribosomes and centrosomes.
What shape are human cheek cells?
They are flat and polygonal.
How should the sample be spread when preparing onion-peel and cheek-cell mounts?
Spread the material uniformly on the slide.
Which scientists explained plasma membrane structure using the fluid mosaic model?
Singer and Nicolson.
How do oxygen and carbon dioxide cross the plasma membrane?
They pass freely by diffusion.
What three functions does the plasma membrane perform?
It protects cell components, gives the cell shape, and permits materials to pass through tiny pores.
How does plasma membrane flexibility enable Amoeba to take in food?
It enables endocytosis.
How do exterior sugar chains on plasma membrane proteins and lipids help cells?
They help cells interact with other cells’ surface molecules.
Where does carbon dioxide move during cellular respiration?
It diffuses out of the cell.
Where does oxygen move during cellular respiration?
It diffuses from the external medium into cells.
What is endocytosis?
The uptake of bulk material from the external environment into a cell.
What are the two forms of endocytosis named in this unit?
Phagocytosis and pinocytosis.
How does a hypotonic solution compare with cell contents?
It is more dilute and has higher water content.
What may happen to an animal cell in a hypotonic solution?
It swells and may burst.
Why does a plant cell resist bursting in a hypotonic solution?
Its cell wall prevents it from bursting.
How does an isotonic solution compare with cell contents?
It has the same concentration as the cell contents.
What happens to cell size in an isotonic solution?
It remains unchanged.
How does a hypertonic solution compare with cell contents?
It is more concentrated and has lower water content.
How can cells differ in function?
They can specialize for specific functions.
Which scientist discovered cells, and in what year?
Robert Hooke, 1665.
What did Robert Hooke observe when he discovered cells?
A cork slice through a primitive microscope.
What is the cell wall’s position relative to the plasma membrane?
Outside the plasma membrane.
What are two properties of the cell wall?
It is rigid and freely permeable.
Which organisms have cell walls, according to the statement?
Plants, bacteria, blue-green algae, some protists, and all fungi.
Which cells lack a cell wall?
Animal cells.
What does a living Rheo leaf peel show in strong sugar or salt solution?
Plasmolysis.
Which cells can exhibit osmosis or absorb water by osmosis?
Living cells with selectively permeable membranes.
What separates the nucleoplasm from the cytoplasm and exchanges substances between them?
The two-membrane nuclear envelope, which contains pores.
What does the nucleoplasm contain?
Chromatin threads and the nucleolus.
Who is credited with discovering the nucleolus?
Fontana.
What do chromatin threads organize into before cell division?
Chromosomes.
What is cytosol?
The aqueous, nearly transparent, structureless ground substance inside the cell.
What are cell organelles?
Subcellular structures with characteristic forms, structures, and functions; almost all are membrane-bound.
Where are proteins made by free ribosomes used?
Inside the cell.
Which subunits make up eukaryotic ribosomes?
60S and 40S subunits.
What is the endoplasmic reticulum?
A network of membrane-bound channels, sheets, tubules, and vesicles found throughout the cell.
Which scientist discovered the Golgi complex in owl nerve cells, and when?
Camillo Golgi discovered it in 1898.
Where is the Golgi complex located, and what type of membrane surrounds it?
Near the nucleus; it is single-membrane-bound.
In which direction do materials move through the Golgi complex?
From the cis face to the trans face in vesicles.
Which structures does the Golgi complex form?
Lysosomes, secretory vesicles, and the sperm acrosome.
What does the sperm acrosome contain, and what does it dissolve?
Lytic enzymes that dissolve the egg membrane during fertilization.
Which cell products and structures are formed at the Golgi complex?
Glycolipids, glycoproteins, cell-wall polysaccharides, and plant cell plates.
Where are lysosomal enzymes produced?
In the rough endoplasmic reticulum.
What may lysosomes digest besides food?
The cell after it dies.
What folds increase mitochondrial inner membrane surface area?
Cristae.
Answer 59 questions on The Fundamental Unit of Life.
1. Which description best captures the role of a cell in a living organism?
2. Which observation is associated with Robert Hooke’s work in 1665?
Go over the full study guide for The Fundamental Unit of Life.
Read the study guide →Upload your class notes and Revizly writes your flashcards in about a minute.
Flashcard maker