Biology Chapter I: Living Organisms and Cells

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Questions and Answers

What is the function of ribosomes in prokaryotic cells?

DNA replication

Cell division

Energy production

Protein production (correct)

Which structure in prokaryotic cells is responsible for motility?

Flagellum (correct)

Nucleoid

Ribosome

Plasmid

What unique feature differentiates eukaryotic cells from prokaryotic cells?

Method of reproduction

Size of the cell

Presence of a nucleus (correct)

Cell wall composition

What is the role of a bacterial capsule?

Protection from toxins and adhesion Signup and view all the answers

In eukaryotic cells, what is the function of the endoplasmic reticulum?

Membrane-bound compartments for metabolic reactions Signup and view all the answers

What is the primary mode of reproduction in prokaryotes?

Binary fission Signup and view all the answers

What constitutes the nucleus in eukaryotic cells?

DNA-protein complex called chromatin Signup and view all the answers

Which of the following is NOT a component of prokaryotic cells?

Nucleus Signup and view all the answers

What is one of the fundamental abilities of living organisms?

Ability to grow and reproduce Signup and view all the answers

Which type of environment produces energy through fermentation?

Anaerobic environment Signup and view all the answers

Which structure is characteristic of prokaryotic cells?

Cell wall Signup and view all the answers

What distinguishes Gram-positive bacteria from Gram-negative bacteria?

Thickness of the peptidoglycan layer Signup and view all the answers

What is the primary substance making up prokaryotic cytoplasm?

Gel-like water Signup and view all the answers

What is the main function of mitochondria in eukaryotic cells?

Production of energy in the form of ATP Signup and view all the answers

Which structure in plant cells is responsible for intercellular communication?

Plasmodesmata Signup and view all the answers

Which of the following is NOT considered an essential element of prokaryotic cells?

Mitochondria Signup and view all the answers

Which of the following describes prokaryotic organisms?

They can be free-living or parasitic. Signup and view all the answers

What is a key characteristic of the Golgi apparatus?

It is a series of flattened, stacked membranes Signup and view all the answers

What is the fundamental unit of life in living organisms?

Cell Signup and view all the answers

What role does the cytoskeleton play in eukaryotic cells?

Transportation of vesicles and maintenance of cell shape Signup and view all the answers

What substance do peroxisomes contain that has a role in the breakdown of hydrogen peroxide?

Enzymes Signup and view all the answers

What distinguishes the smooth endoplasmic reticulum from the rough endoplasmic reticulum?

The presence of ribosomes on its surface Signup and view all the answers

Which component is not found in animal cells?

Cell wall Signup and view all the answers

Which organelle is involved in the metabolic reactions leading to energy production in cells?

Mitochondria Signup and view all the answers

Study Notes

Chapter I: The Living Organism and the Cell

This chapter covers living organisms and the fundamental unit of life, the cell.
Living organisms possess the ability to acquire energy from organic matter (e.g., glucose, galactose). Energy production occurs via fermentation (anaerobic) or respiration (aerobic).
Living organisms reproduce, grow and differentiate.
They possess genetic material encoding enzymatic and non-enzymatic elements crucial for vital functions.
The fundamental unit of life is the cell. Cells can be single-celled (unicellular) or multi-celled (multicellular).
Living organisms perform catabolism (degradation of biomolecules) and anabolism (synthesis of biomolecules).

Kingdoms of the Living Things

Organisms are classified into five kingdoms: Monera, Protista, Plantae, Fungi, and Animalia.
Monera are prokaryotic and unicellular.
Protista are eukaryotic and unicellular or multicellular. They can have cell walls.
Plantae are eukaryotic and multicellular, with cell walls.
Fungi are eukaryotic and multicellular, with cell walls.
Animalia are eukaryotic and multicellular, without cell walls.

I: Prokaryotic Cell

Prokaryotes are the most primitive life forms, simple, single-celled organisms.
Prokaryotes include bacteria and archaeabacteria.
They can be free-living, photosynthetic, parasitic (living inside other organisms) or saprophytic (feeding on dead/decaying matter).
Prokaryotes exist in various environments - land, water bodies, atmosphere, hydrothermal vents and even inside living organisms.

Prokaryotic Cell Structure

Essential elements:
- Cell wall: External covering, protecting the bacterial cell and giving it shape. Gram-positive bacteria have thick peptidoglycan, Gram-negative have thin peptidoglycan.
- Plasma membrane: Encloses the cytoplasm, regulates substance flow.
- Cytoplasm: Gel-like substance containing water, enzymes, salts, cell components and organic molecules.
- Nucleoid/nuclear area: Region holding the prokaryote's single DNA molecule.
- Ribosomes: Structures responsible for protein production.
Optional elements:
- Plasmid: Small, circular DNA fragment.
- Bacterial capsule: Protective shield.
- Flagellum: Motility organelle.
- Pili: Hair-like projections.
- Chromatophores: Membrane systems (photosynthetic bacteria).
- Gas vacuoles: Help provide buoyancy (aquatic bacteria).

Prokaryotic Reproduction

Prokaryotes reproduce asexually mainly by binary fission.

II: Eukaryotic Cell

Eukaryotes have a true nucleus and membrane-bound organelles.
Eukaryotes include single and multi-celled organisms (plants, animals, fungi, protists)
Eukaryotic cells are generally larger (10-100 µm) than prokaryotic cells.
Possess well developed endomembrane system compared to prokaryotic cells.
Contains organelles that perform specialized physiological functions for diverse metabolic reactions.

Eukaryotic Cell Structure

Nucleus: Contains genetic material, bounded by a double membrane called the nuclear envelope
Plasma membrane: Similar structure to in prokaryotes.
Cytoplasm: Contents within the plasma membrane excluding the nucleus.
Endoplasmic reticulum (ER): A membrane network. Rough ER has ribosomes, smooth ER lacks them.
Golgi apparatus: Stacked membrane sacs, involved in modifying and packaging substances.
Mitochondria: Sites for cellular respiration (ATP production).
Cytoskeleton: Network of protein filaments, supporting structure and aiding movement.
Peroxisomes: Contain enzymes that break down hydrogen peroxide.
Lysosomes: Contain hydrolase enzymes for breaking down waste.

III: Animal Eukaryotic Cell

Centrosoma: A organelle near the nucleus, where microtubules are formed/made.

IIII: Plant Eukaryotic Cell

Cell wall: Surrounds the plasma membrane; composed of cellulose, hemicellulose, pectin, lignin.
Vacuole: Membrane-bound compartment storing water and various molecules.
Plastids: Organelles like chloroplasts (photosynthesis), found in plants and algae.
Plasmodesmata: Cytoplasmic bridges connecting plant cells, enabling cell communication.

III: Acaryotes (Viruses)

Viruses are small, infectious agents that need a host cell to replicate.
Viruses have either DNA or RNA as genetic material.
Viruses have three main components:
- Nucleic acid: DNA or RNA.
- Capsid: Protein coat protecting the nucleic acid.
- Envelope (optional): Lipid layer acquired from the host cell. Some viruses have envelopes, some don't.

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Explore the fundamental concepts of living organisms and cells in this quiz. Understand energy acquisition, reproduction, and the classification of life forms into various kingdoms. Test your knowledge on the distinguishing features of unicellular and multicellular organisms.