Biology Chapter: Cells and Organisms

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Questions and Answers

At what temperature do thermophiles typically grow best?

80°C - 110°C

40°C - 50°C

15°C - 25°C

50°C - 60°C (correct)

Which of the following statements about Archaea is correct?

They lack cell walls.

They include some extremophiles. (correct)

They have well-defined nuclei.

They are universally larger than bacteria.

Which is NOT a characteristic of the kingdom Fungi?

Cell walls made of chitin

Non-motile

Decomposers

Photosynthetic (correct)

What type of reproduction is primarily associated with Plantae?

Sexual reproduction only Signup and view all the answers

Which group does NOT fall under the classification of Plantae?

Archaea Signup and view all the answers

Which type of organism is known for its ability to thrive in acidic environments?

Acidophiles Signup and view all the answers

What is a distinguishing feature of Protista?

They are not fungi, animals, or plants. Signup and view all the answers

Why are fungi considered important in ecosystems?

They are the best decomposers. Signup and view all the answers

What is the function of enzymes in biochemical reactions?

They speed up metabolic processes without changing themselves. Signup and view all the answers

What can cause proteins to become denatured and non-functional?

Inconsistent temperature or pH levels Signup and view all the answers

Which component is NOT part of a nucleotide?

Amino acid Signup and view all the answers

Which type of cell contains a cell wall made of cellulose?

Plant cells Signup and view all the answers

Which nucleotides are components of RNA?

A, G, C, U Signup and view all the answers

What is the primary role of adenosine triphosphate (ATP) in cells?

To carry energy Signup and view all the answers

What is the structure of DNA?

Double-stranded helix Signup and view all the answers

What type of bonds connect the nitrogenous bases in DNA?

Hydrogen bonds Signup and view all the answers

What is the primary role of cells in living organisms?

Cells are the basic units of structure and function. Signup and view all the answers

How can one differentiate between an organ and a tissue?

By its ability to perform multiple functions. Signup and view all the answers

Which of these is NOT considered a basic building block of life?

Organs Signup and view all the answers

What distinguishes cells from one another?

Their size, shape, structure, and function. Signup and view all the answers

What is an example of a tissue?

Xylem Signup and view all the answers

What represents the smallest common denominator of life?

Cell Signup and view all the answers

Which of the following is an organ?

Liver Signup and view all the answers

What is a key distinction between active and passive transport in cells?

Active transport requires energy; passive transport does not. Signup and view all the answers

What type of organisms are classified as Animalia?

Multicellular, heterotrophic eukaryotes capable of mobility at some life stage Signup and view all the answers

Which of the following elements constitute 96.5% of all atoms in an organism?

Carbon, hydrogen, oxygen, nitrogen Signup and view all the answers

What type of bond is formed by the unequal sharing of electrons?

Polar covalent bond Signup and view all the answers

What defines a prokaryotic cell?

Unicellular and lacks a nucleus Signup and view all the answers

Which statement is true about ionic bonds?

They involve the gain and loss of electrons Signup and view all the answers

Which of the following best defines multicellular organisms?

Organisms made of multiple cells working together Signup and view all the answers

What type of interaction is a hydrogen bond?

An attraction between a hydrogen atom and an electronegative atom Signup and view all the answers

Which of the following is NOT true regarding eukaryotic cells?

They lack a defined nucleus Signup and view all the answers

What is the primary role of microtubules in the context of motor protein movement?

Facilitate the movement of molecular motors like kinesins and dyneins Signup and view all the answers

Which of the following functions is NOT associated with lysosomes?

Synthesizing cholesterol Signup and view all the answers

Which statement about intermediate filaments is accurate?

They provide structural support and resist mechanical stress. Signup and view all the answers

How does Taxol (paclitaxel) affect microtubules?

It prevents tubulin subunits from dissociating, stabilizing microtubules. Signup and view all the answers

Which of the following statements about peroxisomes is true?

They digest fatty acids and participate in cholesterol synthesis. Signup and view all the answers

What is the function of colchicine in relation to microtubules?

It causes microtubules to disappear, particularly in inflammatory conditions. Signup and view all the answers

What characteristic distinguishes kinesins from dyneins?

Kinesins usually move toward the plus ends of microtubules. Signup and view all the answers

What type of diseases could be caused by defective intermediate filaments?

Inherited skin-blistering disorders due to keratin mutations. Signup and view all the answers

Study Notes

Cells: The Basic Units of Life

Cells are the fundamental building blocks of all living organisms.
They are the smallest unit capable of independent life.
Cells can be distinguished by size, shape, structure, and function.

Types of Organisms

Prokaryotic: Lack a nucleus, single-celled, small size, examples include Bacteria and Archaea.
Eukaryotic: Have a nucleus, can be single-celled or multicellular, larger in size, examples include Protista, Fungi, Plantae, and Animalia.

The Chemical Components of Cells

Essential Elements: C, H, O, and N make up the majority of an organism's atoms.
Electrolytes: K, Na, Cl, Mg, P, Ca, Fe, and I are important for various cellular functions.
Covalent Bonds: Electrons are shared equally or unequally between atoms.
- Non-polar: Electrons are shared equally (e.g., C-C, C-H bonds).
- Polar: Electrons are shared unequally due to differences in electronegativity.
Ionic Bonds: Atoms gain or lose electrons, forming charged ions that attract each other.
Hydrogen Bonds: Weak interactions between a hydrogen atom and a highly electronegative atom (like oxygen or nitrogen).

Essential Molecules

Proteins: Large, complex molecules made up of amino acids.
- Functions: Regulation, structure, signaling, transport, catalysis, motor proteins.
- Enzymes: Biological catalysts that speed up chemical reactions.
  - Specificity: Enzymes catalyze specific reactions.
  - Reversible reactions: Enzymes can facilitate both forward and reverse reactions.
  - Coenzymes: Some enzymes require a coenzyme or cofactor for activity.
  - Factors affecting enzyme activity: Temperature, pH, enzyme concentration, substrate concentration.
Nucleotides: Monomers of nucleic acids (DNA and RNA).
- Components: Nitrogenous base, sugar, phosphate groups.
- RNA: A, G, C, U, mostly single-stranded.
- DNA: A, G, C, T, double-stranded helix.
ATP: Adenosine triphosphate is the primary energy carrier in cells.

Eukaryotic Cell Structure

Cell Wall: Found in plants, fungi, and bacteria, provides protection, structure, and support.
- Composed of: Cellulose (plants), chitin (fungi), peptidoglycan (bacteria).
Cell Membrane: Encloses the cell and regulates what enters and exits.
- Composed of: Phospholipid bilayer with embedded proteins.
Cytoplasm: The gel-like substance within the cell that houses the organelles.
Nucleus: Contains the cell's genetic material (DNA).
Ribosomes: Sites of protein synthesis.
Endoplasmic Reticulum (ER): Network of membranes involved in protein synthesis and lipid metabolism.
- Rough ER: Has ribosomes attached, involved in protein synthesis.
- Smooth ER: Lacks ribosomes, involved in lipid synthesis and detoxification.
Golgi Apparatus: Processes and packages proteins and lipids for secretion or delivery to other organelles.
Lysosomes: Contain digestive enzymes that break down cellular waste products and ingested materials.
Peroxisomes: Small vesicles involved in fatty acid and alcohol metabolism, cholesterol synthesis, and amino acid digestion.
Mitochondria: Powerhouses of the cell, responsible for cellular respiration and energy production.
Chloroplasts: Found in plant cells, responsible for photosynthesis.
Vacuoles: Storage compartments for water, nutrients, and waste products.
Cilia and Flagella: Hair-like or whip-like structures for movement.
Cytoskeleton: Network of protein fibers that provides structural support and enables cell movement.
- Microtubules: Hollow tubes made of tubulin, involved in cell shape, organelle movement, and cell division.
  - Functions: Mitotic spindle formation, cilia and flagella structure, viral movement.
- Microfilaments: Solid rods made of actin, involved in muscle contraction, cell shape, and movement.
  - Functions: Muscle contraction, cytoplasmic streaming.
- Intermediate Filaments: Resilient networks of protein fibers, providing structural support and resisting mechanical stress.
  - Functions: Structural support, resistance to mechanical stress.

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Description

Explore the fundamental units of life with this quiz on cells. You will learn about the differences between prokaryotic and eukaryotic organisms and the essential chemical components that make up cells. Test your understanding of these foundational concepts in biology.