Cell Structures and Functions
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In many cells, the structure that controls the cell's activities is the...

Nucleolus

Despite differences in size and shape, at some point all cells have DNA and a...

Cell Membrane

What distinguishes a eukaryotic cell from a prokaryotic cell?

A Nucleus

What are the contributions to the cell theory by Robert Hooke, Matthias Schleiden, Theodor Schwann, and Rudolf Virchow?

<p>Robert Hooke discovered the cellular composition of cork; Matthias Schleiden discovered that plants are made of cells; Theodor Schwann discovered that animals are made of cells; Rudolf Virchow stated that all living things come from other living things.</p> Signup and view all the answers

If you wanted to observe a living organism–an amoeba, for example–which type of microscope would you use?

<p>An Electron Microscope (Light)</p> Signup and view all the answers

How are prokaryotic and eukaryotic cells alike, and how do they differ?

<p>They both carry genetic information and are the simplest forms of life. They differ because eukaryotic cells consist of a nucleus and complex membrane-enclosed organelles.</p> Signup and view all the answers

In eukaryotic cells, chromosomes carrying genetic information are found in the...

<p>Cell Nucleus</p> Signup and view all the answers

The organelles that break down lipids, carbohydrates, and proteins into small molecules are called...

<p>Lysosomes</p> Signup and view all the answers

Cell membranes consist mainly of...

<p>Lipid Bilayers</p> Signup and view all the answers

What is the function of a ribosome?

<p>Ribosomes are the cellular components that make proteins.</p> Signup and view all the answers

Describe the role of the Golgi Apparatus.

<p>The Golgi apparatus's main function is modifying, sorting, and packaging proteins for secretion.</p> Signup and view all the answers

Which type of cell structure(s) might produce enzymes used in the pancreas?

<p>The endoplasmic reticulum creates ribosomes that synthesize proteins; ribosomes would most likely produce enzymes.</p> Signup and view all the answers

Indicate if the structure is found only in eukaryotes or prokaryotes: cell membrane, mitochondria, ribosome, Golgi apparatus, nucleus, cytoplasm, and DNA.

<p>Cell membrane: both; mitochondria: only eukaryotes; nucleus: only eukaryotes; ribosomes: both; Golgi apparatus: only eukaryotes; cytoplasm: both; DNA: both.</p> Signup and view all the answers

The movement of water molecules across a selectively permeable membrane is known as...

<p>Osmosis</p> Signup and view all the answers

A substance that moves by passive transport tends to move...

<p>Away from the area where it is more concentrated.</p> Signup and view all the answers

Describe the process of diffusion and explain equilibrium.

<p>Diffusion is the intermingling of substances by the natural movement of their particles. Equilibrium occurs when a process and its reverse occur at equal rates.</p> Signup and view all the answers

What is the relationship between diffusion and osmosis? By definition, what is the only substance that undergoes osmosis?

<p>Diffusion and osmosis both regard the dispersion of particles. Water is the only substance that undergoes osmosis.</p> Signup and view all the answers

What is the difference between passive transport and active transport?

<p>Active transport is the movement of ions or molecules across a membrane into a region of higher concentration, requiring energy; passive transport does not require energy, being driven by entropy.</p> Signup and view all the answers

What would happen to a sample of red blood cells if they were placed in a hypotonic solution?

<p>The water would rush into the cell, causing it to swell and potentially burst.</p> Signup and view all the answers

Design an experiment to determine the effects of temperature on the rate of diffusion.

<p>Drop an equal amount of food coloring into each beaker. My hypothesis is that hot water will diffuse the food coloring faster.</p> Signup and view all the answers

Which of the following is true of ALL single-celled organisms?

<p>They all reproduce.</p> Signup and view all the answers

A tissue is composed of a group of...

<p>Similar Cells</p> Signup and view all the answers

Explain the relationship among cell specialization, multicellular organisms, and homeostasis.

<p>In multicellular organisms, each cell has a specialized role to maintain homeostasis.</p> Signup and view all the answers

Describe the relationship among cells, tissues, organs, and organ systems.

<p>Groups of similar cells form tissues; different tissues work together as organs; organs form organ systems.</p> Signup and view all the answers

Would you expect skin cells to contain more or fewer mitochondria than muscle cells?

<p>Fewer; muscles need more energy for movement.</p> Signup and view all the answers

If a person needs a pacemaker, what does that suggest about his or her heart cells' ability to send and receive chemical messages?

<p>It suggests they may have lost some ability to send or respond to chemical messages.</p> Signup and view all the answers

Classify each of the following cells as prokaryotic or eukaryotic.

<p>Prokaryotes: Escherichia coli, Streptococcus pneumoniae; eukaryotes: human erythrocyte, human ovum, Saccharomyces cerevisiae.</p> Signup and view all the answers

Compare the sizes of prokaryotic cells and eukaryotic cells.

<p>Prokaryotes are smaller than eukaryotes.</p> Signup and view all the answers

Is Chlamydomonas reinhardtii more likely a prokaryotic or eukaryotic organism?

<p>Most likely eukaryote because of the diameter.</p> Signup and view all the answers

Should companies that market high-solute drinks say that the drinks quench thirst?

<p>No, they should not; high solute drinks can dehydrate by moving water out of cells.</p> Signup and view all the answers

What is the relationship between active transport and homeostasis? Give one example of active transport in an organism.

<p>Active transport helps maintain homeostasis; for example, an amoeba uses phagocytosis to take in food.</p> Signup and view all the answers

By approximately what percentage is a molecule of carbon dioxide smaller than a molecule of glucose?

<p>75%</p> Signup and view all the answers

Based on the graph shown, what is a logical hypothesis?

<p>Carbon dioxide crosses the cell membrane faster than glucose.</p> Signup and view all the answers

Animal cells have all the following EXCEPT...

<p>Chloroplasts</p> Signup and view all the answers

The nucleus includes all the following structures EXCEPT...

<p>Cytoplasm</p> Signup and view all the answers

The human brain is an example of a(n)...

<p>Organ</p> Signup and view all the answers

Which cell structures are sometimes found attached to the endoplasmic reticulum?

<p>Ribosomes</p> Signup and view all the answers

Which process always involves the movement of materials from inside the cell to outside the cell?

<p>Exocytosis</p> Signup and view all the answers

Which of the following is an example of active transport?

<p>Endocytosis</p> Signup and view all the answers

The difference between prokaryotic and eukaryotic cells involves the presence of...

<p>A Nucleus</p> Signup and view all the answers

In this experiment, sucrose probably entered the cells by means of...

<p>Endocytosis</p> Signup and view all the answers

The graph shows that as the concentration of sucrose increased from 10 to 30 mmol/L, the plant cells...

<p>Took in sucrose more quickly.</p> Signup and view all the answers

Based on the graph, the rate of sucrose uptake...

<p>Was constant between 30 and 40 mmol/L.</p> Signup and view all the answers

What would you expect to happen if you placed a typical cell in fresh water?

<p>I would expect active transport of water into the cell, causing it to swell and burst.</p> Signup and view all the answers

Study Notes

Cell Structures and Functions

  • Nucleus: Controls cell activities, contains chromatin for DNA packaging and gene regulation, features a nucleolus for ribosomal RNA synthesis.
  • Cell Membrane: Present in all cells, consists mostly of lipid bilayers, regulates the passage of materials.
  • Chromosomes: In eukaryotic cells, these carry genetic information located within the nucleus.
  • Ribosomes: Sites of protein synthesis, created by the endoplasmic reticulum and nucleolus, vital for cell function.

Types of Cells

  • Eukaryotic vs Prokaryotic: Eukaryotic cells contain a nucleus and organelles like mitochondria and Golgi apparatus; prokaryotic cells lack these structures and are generally smaller.
  • Cellular Composition: Prokaryotes (e.g., E. coli) have simple structures, while eukaryotes (e.g., human ovum) possess complex organelles.

Cell Theory

  • Key Contributors:
    • Robert Hooke: First described cells in cork (1665).
    • Matthias Schleiden: Proposed that plants are made of cells (1838).
    • Theodor Schwann: Proposed that animals are composed of cells (1839).
    • Rudolf Virchow: Asserted all cells arise from pre-existing cells.

Transport Mechanisms

  • Osmosis: Movement of water across selectively permeable membranes towards areas of higher solute concentration.
  • Diffusion: Natural movement of particles from areas of high concentration to low, leading to equilibrium.
  • Passive vs Active Transport: Passive transport does not require energy (e.g., diffusion), whereas active transport requires energy to move substances against concentration gradients.

Cellular Processes

  • Endocytosis: Process used by cells to take in substances, including sucrose.
  • Exocytosis: Movement of materials from inside the cell to the outside, essential for waste removal and secretion.
  • Lysosomes: Organelles that break down complex molecules like lipids and proteins.

Relationships in Biological Systems

  • Cell Specialization: In multicellular organisms, specialized cells work together to maintain homeostasis.
  • Hierarchy of Biological Organization: Cells form tissues, tissues form organs, and organs work together as organ systems.

Experimental Observations

  • Influence of Temperature on Diffusion: Higher temperatures increase the rate of diffusion due to more molecular collisions.
  • Impact of Solutions on Cells: Cells in hypotonic solutions can swell and burst due to excess water uptake.

Miscellaneous

  • Size Comparison: Prokaryotic cells are typically smaller than eukaryotic cells.
  • Cell Types: Animal cells lack chloroplasts, while plants contain them for photosynthesis.
  • Mitochondria Quantity: Muscle cells have more mitochondria than skin cells due to higher energy demands.

Sucrose Uptake Experiment

  • Rate of Uptake: As sucrose concentration increases, plant cells absorb sucrose more rapidly until a plateau is reached.

Key Definitions

  • Equilibrium: State where diffusion occurs at equal rates in both directions, resulting in no net change in concentration.
  • Hypothesis Example: Hot water will cause food coloring to diffuse faster due to enhanced molecular activity.

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Description

Explore the fundamental components of cells, including their structures and functions. This quiz covers the differences between eukaryotic and prokaryotic cells, molecular composition, and historical contributions to cell theory. Test your knowledge of key cellular concepts and definitions.

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