Biology 10th Class: Cell Structure and Function

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Questions and Answers

Which of the following scientists was the first to observe a living cell?

Robert Hooke

Anton van Leeuwenhoek (correct)

Matthias Schleiden

Theodore Schwann

What was the main feature that Robert Hooke observed when he examined a thin piece of cork?

Cell walls (correct)

Cytoplasm

Mitochondria

The nucleus

Which of the following organelles are involved in the process of manufacturing, distribution, and breakdown within a cell?

Lysosomes, Vacuole, Centrioles

Endoplasmic reticulum, Ribosome, Golgi apparatus (correct)

Nucleus, Golgi apparatus, Mitochondria

Cell membrane, Cell wall, Cytoplasm

Which of the following organelles are involved in the direct production of energy within a cell?

Mitochondria, Chloroplasts (C) Signup and view all the answers

What is the correct order of biological organization from smallest to largest?

Cells, Tissues, Organs, Organ Systems, Organism (A) Signup and view all the answers

Which of the following organelles is responsible for the production of ribosomes within a cell?

Nucleolus (B) Signup and view all the answers

According to cell theory, all living things are made of _____.

Cells (B) Signup and view all the answers

Which of the following is NOT a component of the cytoskeleton?

Cell membrane (B) Signup and view all the answers

Which scientist is credited with observing cell division?

Rudolph Virchow (C) Signup and view all the answers

What is the primary difference between the observations made by Robert Hooke and Anton van Leeuwenhoek?

Hooke observed a living cell, while Leeuwenhoek observed a dead cell. (D) Signup and view all the answers

Which of the following statements is true about the cell membrane?

It is composed of a phospholipid bilayer. (A) Signup and view all the answers

Which of the following statements is NOT part of the cell theory?

Cells can spontaneously arise from non-living matter. (D) Signup and view all the answers

Which two scientists are credited with concluding that all plants and all animals are made of cells?

Schleiden and Schwann (A) Signup and view all the answers

Which of the following statements correctly describes the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells are simpler and smaller than eukaryotic cells, lacking a nucleus and other membrane-bound organelles. (B) Signup and view all the answers

Which of the following is a characteristic of prokaryotic cells?

They possess a single, circular chromosome. (B) Signup and view all the answers

Which of the following is NOT a type of eukaryotic cell?

Bacteria (A) Signup and view all the answers

What is the function of ribosomes in prokaryotic cells?

To synthesize proteins (D) Signup and view all the answers

Which of the following is a reason why cells tend to be small?

Smaller cells are more efficient at transporting materials across their membranes. (C) Signup and view all the answers

Which of the following statements is TRUE about the size of different types of cells?

Plant cells are typically larger than bacterial cells. (D) Signup and view all the answers

What is the main reason that eukaryotic cells have a more complex structure than prokaryotic cells?

Eukaryotic cells need to be able to carry out a wider range of functions. (D) Signup and view all the answers

Which of the following is a key difference between plant and animal cells?

Plant cells have chloroplasts, while animal cells do not. (B) Signup and view all the answers

What does the surface area to volume ratio limit in cells?

The rate of diffusion of materials across the cell membrane (B) Signup and view all the answers

When a cell becomes larger, what happens to its surface area to volume ratio?

The surface area decreases more rapidly than the volume (C) Signup and view all the answers

What is the main difference between a unicellular organism and a multicellular organism?

Unicellular organisms consist of one cell, while multicellular organisms consist of many cells (A) Signup and view all the answers

What is cell differentiation?

The process by which cells become specialized to perform specific functions (C) Signup and view all the answers

Which of the following is NOT a specialized animal cell?

Guard cell (D) Signup and view all the answers

What is the function of xylem cells in plants?

To transport water and dissolved nutrients upward (D) Signup and view all the answers

What is the difference between a membrane bound and a non-membrane bound organelle?

A membrane-bound organelle has a membrane surrounding it, while a non-membrane bound organelle does not (B) Signup and view all the answers

What is the role of organelles in a cell?

To carry out specific functions within the cell (D) Signup and view all the answers

What is the primary function of chloroplasts?

Convert sunlight into chemical energy through photosynthesis (B) Signup and view all the answers

Which component of the chloroplast contains thylakoids?

Stroma (A) Signup and view all the answers

What is the structural arrangement of thylakoids within chloroplasts?

Stacked in interconnected grana (D) Signup and view all the answers

What distinguishes chloroplasts from other organelles?

Ability to replicate their own DNA (A) Signup and view all the answers

What is the role of the smooth outer membrane of chloroplasts?

Protect and organize chloroplast structure (D) Signup and view all the answers

What is the primary role of the nucleolus in a cell?

To produce ribosomes (A) Signup and view all the answers

What cellular process is facilitated by mitochondria?

Cellular respiration (D) Signup and view all the answers

Which structures are exclusively found in animal cells?

Centrioles (A) Signup and view all the answers

How do mitochondria acquire their DNA?

From the mother during fertilization (D) Signup and view all the answers

What is the primary function of centrioles during cell division?

To help pull chromosomes apart (B) Signup and view all the answers

What enhances the effectiveness of mitochondria in energy production?

Folded inner membrane (cristae) (B) Signup and view all the answers

Which of the following is NOT a basic function of organelles listed?

Cell signaling (D) Signup and view all the answers

Which organelle is often referred to as the 'power plant' of the cell?

Mitochondria (C) Signup and view all the answers

Study Notes

Cells: The Basic Unit of Life

Cells are the fundamental building blocks of all living things.
Some organisms are single-celled, others are multicellular.
Multicellular organisms are organized into levels: cells, tissues, organs, and organ systems.

Cell Theory

All living things are made of cells.
Cells are the basic unit of structure and function in an organism.
Cells come from the reproduction of existing cells (cell division).

History of Cell Discovery: Hooke

In 1665, Robert Hooke used a primitive microscope to examine cork.
He observed small compartments and named them "cells" because they resembled small rooms monks lived in.

History of Cell Discovery: Leeuwenhoek

In 1673, Anton van Leeuwenhoek was the first to view a live cell using a simple handheld microscope.
He observed pond water samples and various other materials.

History of Cell Discovery: Schleiden & Schwann

In 1838, Matthias Schleiden (botanist) concluded that all plants were made of cells.
In 1839, Theodore Schwann (zoologist) concluded that all animals were made of cells.

History of Cell Discovery: Virchow

In 1855, Rudolph Virchow observed dividing cells and stated that all cells come from pre-existing cells.

Cell Size Variation

Bacterial cells are typically 0.1 – 5 μm.
Animal cells are generally 10 – 30 μm.
Plant cells range from 10 – 100 μm.
Cell size is limited by the ratio of surface area to volume.

Why are Cells Small?

Nutrients and waste are exchanged at the cell's membrane.
As a cell grows, volume increases faster than surface area.

Number of Cells

Organisms can be unicellular (one-celled) or multicellular (many cells).
Multicellular organisms often have specialized cells.

Cell Specialization

Cells in multicellular organisms specialize to perform specific functions.
This process is called differentiation.

Specialized Animal Cells

Examples include muscle cells, red blood cells, and cheek cells (epithelial cells).

Specialized Plant Cells

Examples include guard cells (for gas exchange) and xylem cells (for transporting water and nutrients).

Cell Parts (Organelles)

Organelles are specialized structures within a living cell.
They perform specific functions.
Some organelles have membranes; others do not.

Prokaryotes

Prokaryotic cells lack a nucleus and other membrane-bound organelles.
Prokaryotes are the simplest type of cell, believed to have evolved first.
Prokaryotic cells have a single circular chromosome.
Prokaryotic cells include bacteria.

Prokaryotic Cell Structure

Nucleoid region: contains the cell's DNA.
Cell membrane and cell wall surround the nucleoid region.
Ribosomes are present in the cytoplasm for protein synthesis.

Eukaryotes

Eukaryotic cells have a nucleus and other membrane-bound organelles.
Eukaryotic cells are more complex than prokaryotic cells.
They include protists, fungi, plants, and animals.

Eukaryotic Cell Structure

Nucleus: contains the DNA and controls cellular activities.
Nuclear envelope: the membrane surrounding the nucleus, has pores for material exchange.
Cytoplasm: the jelly-like substance that fills the cell and surrounds organelles.
Cell membrane: the outer boundary of the cell, controls the entry and exit of materials.
Cytoskeleton: a network of proteins that give the cell shape, support, and movement, and help move organelles around.

Organelles

Mitochondria: the power plants of cells, generate energy (ATP) by breaking down glucose.
Chloroplasts: found only in plants and algae, use sunlight to make energy in a process called photosynthesis.
Endoplasmic reticulum (ER): a network of membranes that synthesize and transport cell products (proteins and lipids)
- Rough endoplasmic reticulum has ribosomes on its surface, involved in protein synthesis
  - Smooth endoplasmic reticulum synthesized lipids, regulates calcium, and breaks down toxins.
Ribosomes: "protein factories" of the cell, make proteins.
Golgi apparatus: modifies, sorts, and packages cell products from the ER for transport.
Lysosomes: break down food, bacteria, and worn-out cell parts in cells.
Vacuoles: fluid-filled sacs for storage (large in plant cells, small or absent in animal cells).
Centrosomes: important for cell division; contain centrioles.
Cilia and Flagella: structures for cell movement.

Endosymbiosis

Endosymbiotic theory explains the origin of mitochondria and chloroplasts.
It suggests that these organelles were once free-living prokaryotes that were engulfed by a larger cell

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Description

Test your knowledge of cell biology concepts with this quiz designed for 10th-grade students. Questions cover historical contributions, organelle functions, and cell theory. Challenge yourself and see how well you understand the fundamental units of life!