3A1 Structure and Function of Molecules and Organisms

Question 1

Define:

Cell

Answer 1

The basic structural and functional unit of all living organisms.

Cells are the smallest unit of life capable of performing all life processes, such as growth, metabolism, and reproduction.

Question 2

What is the cell membrane?

Answer 2

A selectively permeable barrier that surrounds the cell.

Present in both eukaryotes and prokaryotes, it controls the movement of substances in and out of the cell to maintain homeostasis.

Question 3

What is the primary structure of the cell membrane?

Answer 3

The phospholipid bilayer.

The phospholipid bilayer forms the membrane’s basic structure, with hydrophobic tails facing inward and hydrophilic heads facing outward, creating a semi-permeable barrier.

Question 4

What does selectively permeable mean for a cell membrane?

Answer 4

It allows some substances to pass through while blocking others.

This ensures essential nutrients enter, waste exits, and harmful substances are kept out.

Question 5

True or False:

The phospholipid bilayer is rigid and immobile.

Answer 5

False

The membrane is fluid, allowing components like proteins and lipids to move within the bilayer.

Question 6

Fill in the blank:

The cell membrane is often described as a _______ mosaic.

Answer 6

fluid

Just like a mosaic, the cell membrane is composed of many molecules. This model represents the dynamic and flexible nature of the membrane.

Question 7

What are the functions of membrane proteins?

Answer 7

• Transport
• Signaling
• Structural Support

Protein act as carriers, receptors for signals, and anchors for the cytoskeleton.

Question 8

What role does cholesterol play in the cell membrane?

Answer 8

It maintains membrane fluidity and stability.

Cholesterol prevents the membrane from becoming too stiff in cold temperatures or too fluid in warm temperatures.

Question 9

What is passive transport?

Answer 9

The movement of molecules across the membrane without energy (ATP) input.

It includes diffusion, osmosis, and facilitated diffusion, driven by concentration gradients.

Question 10

True or False:

Active transport requires energy in the form of ATP.

Answer 10

True

Molecules against their concentration gradient, requiring ATP as energy.

Question 11

Fill in the blank:

The movement of large molecules into the cell using vesicles is called _______.

Answer 11

endocytosis

It is a form of active transport that brings substances like nutrients or hormones into the cell.

Question 12

What is the function of glycoproteins in the cell membrane?

Answer 12

Cell recognition and signaling.

They have carbohydrate chains that help cells identify and communicate with each other.

Question 13

What organelles break down fatty acids and detoxify harmful substances?

Answer 13

Peroxisomes

They contain enzymes that metabolize fatty acids and detoxify harmful substances, producing hydrogen peroxide as a byproduct.

Question 14

True or False:

Endocytosis and exocytosis are types of passive transport.

Answer 14

False

These processes involve vesicles and require energy, making them forms of active transport.

Question 15

What is the function of the nucleus in a eukaryotic cell?

Answer 15

It houses the cell’s DNA and controls cellular activities.

The nucleus regulates gene expression, cell growth, and reproduction by controlling the synthesis of proteins and RNA.

Question 16

What organelle is responsible for energy production in eukaryotic cells?

Answer 16

Mitochondrion

Mitochondria produce ATP through cellular respiration, providing energy for the cell’s functions.

Question 17

What is the role of the endoplasmic reticulum (ER)?

Answer 17

It synthesizes proteins and lipids.

The Endoplasmic Reticulum has two main parts, the rough and smooth sections. The rough ER is studded with ribosomes for protein synthesis, while the smooth ER is involved in lipid production and detoxification.

Question 18

What organelle is involved in the production of proteins?

Answer 18

Ribosomes

They are the sites of protein synthesis, translating mRNA into amino acid chains.

Question 19

Fill in the blank:

The chloroplast is responsible for _________ in plant cells.

Answer 19

photosynthesis

Chloroplasts capture sunlight and convert it into chemical energy through photosynthesis, producing glucose and oxygen.

Question 20

True or False:

The vacuole in plant cells stores water, nutrients, and waste products.

Answer 20

True

Vacuoles are large organelles in plant cells that maintain turgor pressure, store nutrients, and play a role in waste management.

Question 21

What organelle assembles rRNA and combines it with proteins to form ribosomes?

Answer 21

Nucleolus

Found in the center of the nucelus, it is the site where ribosomal RNA (rRNA) is produced and combined with proteins to form ribosomes, which are crucial for protein synthesis.

Question 22

True or False:

Cilia and flagella are involved in cell movement.

Answer 22

True

Cilia are short and numerous, moving fluid over the cell’s surface, while flagella are long and whip-like, helping the cell move through its environment.

Question 23

What is the function of the cell wall in prokaryotic cells?

Answer 23

It provides structure and protection.

The cell wall maintains the shape of the prokaryotic cell and protects it from environmental stress.

Question 24

True or False:

Prokaryotic cells have membrane-bound organelles.

Answer 24

False

Prokaryotic cells lack membrane-bound organelles, unlike eukaryotic cells that have structures like the nucleus and mitochondria.

Question 25

# Fill in the blank: The \_\_\_\_\_\_\_\_ helps **prokaryotic cells move** in their environment.

Answer 25

flagella ## Footnote They are long, whip-like structures that aid in motility.

Question 26

What **carries** additional genetic information in prokaryotic cells?

Answer 26

Plasmid ## Footnote They are small, circular DNA molecules that can carry genes, such as those for antibiotic resistance.

Question 27

# True or False: Prokaryotic cells contain a **true nucleus**.

Answer 27

False ## Footnote Prokaryotic cells do not have a true nucleus; their genetic material is not enclosed in a membrane-bound compartment.

Question 28

# Fill in the blank: Prokaryotic cells go through \_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_ for **cell division**.

Answer 28

binary fission ## Footnote It is the method of asexual reproduction in prokaryotic cells, where the cell divides into two identical daughter cells.

Question 29

What is a **virus**?

Answer 29

A microscopic infectious agent that requires a host to replicate. ## Footnote Viruses are **non-living** outside a host but become active once inside a cell. They infect organisms by inserting their genetic material and hijacking the host’s machinery to reproduce.

Question 30

What are **two main components** of a virus?

Answer 30

1. Genetic material (DNA or RNA) 2. Protein coat (capsid) ## Footnote **Genetic material (DNA or RNA)** – Stores viral instructions. **Protein coat (capsid)** – Protects genetic material.

Question 31

What do viruses **need** to reproduce?

Answer 31

A host cell. ## Footnote Viruses cannot reproduce on their own; they must enter a host cell and use its machinery to replicate. This is why they are considered obligate intracellular parasites.

Question 32

# True or False: **Antibiotics** can kill viruses.

Answer 32

False ## Footnote Antibiotics only target **bacteria**, not viruses. Viral infections are treated with antiviral drugs or prevented through vaccines.

Question 33

What are **three types** of human tissues?

Answer 33

1. Epithelial tissue 2. Muscle tissue 3. Nervous tissue ## Footnote **Epithelial tissue** – Covers and protects (e.g., skin). **Muscle tissue** – Allows movement (e.g., heart, skeletal muscles). **Nervous tissue** – Sends signals (e.g., brain, spinal cord).

Question 34

What is a **group** of similar cells performing a specific function called?

Answer 34

Tissue ## Footnote **Tissues** consist of similar cells working together to carry out a particular task, such as muscle tissue or nervous tissue.

Question 35

What comes **after** tissues in the hierarchy of biological organization?

Answer 35

Organs ## Footnote Tissues **form** organs, and organs work together within organ systems to perform complex functions.

Question 36

# Fill in the blank: Groups of organs working **together** to perform a major function form a/an \_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_.

Answer 36

organ system ## Footnote *Organ systems*, like the digestive or respiratory system, consist of multiple organs that collaborate to carry out specific biological functions.

Question 37

What is the function of the **respiratory system**?

Answer 37

To **exchange gases**, such as oxygen and carbon dioxide. ## Footnote It includes organs like the lungs, which facilitate the exchange of gases necessary for cellular respiration.

Question 38

What system **controls and coordinates** body activities?

Answer 38

Nervous system ## Footnote It consists of the brain, spinal cord, and nerves, working together to transmit signals and regulate bodily functions.

Question 39

What organ system **transports** nutrients and oxygen in the body?

Answer 39

The circulatory system ## Footnote The *heart*, *blood*, and *blood vessels* work together to pump oxygen-rich blood throughout the body and remove waste like carbon dioxide.

Question 40

# Fill in the blank: The primary organ of the **excretory system** is the \_\_\_\_\_\_\_.

Answer 40

kidney ## Footnote The **kidneys** filter waste from the blood, forming urine, which is excreted through the urinary system (ureters, bladder, urethra).

Question 41

What is the function of **muscle tissue** in the body?

Answer 41

To **enable** movement. ## Footnote *Muscle tissue* contracts and relaxes to move the body and its parts, as seen in skeletal muscles, heart muscles, and smooth muscles.

Question 42

What is the **largest organ** in the human body?

Answer 42

Skin ## Footnote It protects the body, regulates temperature, and allows sensory perception, making it the largest organ in terms of surface area.

Question 43

# True or False: The digestive system is made up of **only** the stomach and intestines.

Answer 43

False ## Footnote It includes various organs, such as the *mouth*, *esophagus*, *stomach*, and *intestines*, which work together to digest food.

Question 44

Which two systems **interact** to control movement?

Answer 44

* Nervous system * Muscular system ## Footnote The *nervous system* (brain, spinal cord, nerves) sends electrical signals to the *muscular system* (skeletal muscles), allowing voluntary and involuntary movement.

Question 45

What is the main function of **red blood cells**?

Answer 45

To **transport oxygen** throughout the bloodstream. ## Footnote Also called *erythrocytes*, they are specialized for carrying oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs.

Question 46

What is the unique feature of **muscle cells** that enables movement?

Answer 46

They contain contractile proteins, such as **actin** and **myosin**. ## Footnote Muscle cells, or *myocytes*, have specialized proteins that allow them to contract and enable movement in the body.

Question 47

# Fill in the blank: Nerve cells, also known as \_\_\_\_\_\_\_\_, **transmit** electrical signals throughout the body.

Answer 47

neurons ## Footnote These cells allow for communication within the nervous system.

Question 48

What is the function of **epithelial cells**?

Answer 48

To **form protective layers** and secrete substances. ## Footnote These cells line body surfaces and cavities, forming barriers and contributing to secretion and absorption in various organs.

Question 49

# True or False: Epithelial cells are **always** a single layer thick.

Answer 49

False ## Footnote They can be one layer thick (simple epithelium) or multiple layers thick (stratified epithelium), depending on the function and location.

Question 50

# Fill in the blank: Muscle cells are **characterized** by the presence of \_\_\_\_\_\_\_\_, which allow them to contract.

Answer 50

myofibrils ## Footnote **Myofibrils** contain actin and myosin filaments that slide past each other to generate contraction.

Question 51

What cells are involved in the **immune response**?

Answer 51

White blood cells | (leukocytes) ## Footnote They help fight infections by attacking foreign pathogens and producing antibodies.

Question 52

# Fill in the blank: \_\_\_\_\_\_\_\_ cells in the body **help** with gas exchange in the lungs.

Answer 52

Alveolar ## Footnote These cells in the lungs facilitate gas exchange by allowing oxygen to pass into the blood and carbon dioxide to exit.

Question 53

What is unique about the **structure** of red blood cells?

Answer 53

The **biconcave shape** allows the cell to carry more oxygen. ## Footnote The shape increases the cell's surface area, allowing it to efficiently carry and release oxygen.

Question 54

How does a nerve cell **transmit signals** to other nerve cells?

Answer 54

Communication through **axons** and **dendrites**. ## Footnote **Axons** transmit electrical impulses away from the cell body, while **dendrites** receive signals from other neurons, enabling communication across the nervous system.

Question 55

What is the main **difference** between prokaryotic and eukaryotic cells?

Answer 55

**Prokaryotic** cells lack a nucleus, whereas **eukaryotic** cells have one. ## Footnote Prokaryotes are simpler organisms like bacteria, while eukaryotes include plants, animals, fungi, and protists.

Question 56

# True or False: All prokaryotes are **unicellular**.

Answer 56

True ## Footnote Unicellular organisms, like bacteria and archaea, have no membrane-bound nucleus.

Question 57

What are the two main **groups** of prokaryotes?

Answer 57

1. Eubacteria 2. Archaea ## Footnote Eubacteria are typical bacteria, while Archaea are extremophiles, capable of living in harsh environments.

Question 58

What type of cell contains **chloroplasts**?

Answer 58

Plant ## Footnote These organelles responsible for photosynthesis, converting sunlight into chemical energy.

Question 59

# True or False: Archaea can live in **extreme** environments like hot springs and salt lakes.

Answer 59

True ## Footnote They are known as *extremophiles*, thriving in environments with extreme heat, salinity, or acidity.

Question 60

What kind of organisms are **protists**?

Answer 60

Eukaryotic microorganisms. ## Footnote They often unicellular, but some can be multicellular, and they can be autotrophic or heterotrophic.

Question 61

What is the role of **mitochondria** in eukaryotic cells?

Answer 61

They **generate energy** in the form of ATP. ## Footnote *Mitochondria* are known as the powerhouses of the cell, converting nutrients into energy that the cell can use.

Question 62

# True or False: **All** eukaryotic cells have a cell wall.

Answer 62

False ## Footnote **Only** plant cells, fungi, and some protists have a cell wall. Animal cells lack a cell wall.

Question 63

Which group of organisms do **fungi** belong to?

Answer 63

Eukaryotes ## Footnote **Fungi** are a distinct group of eukaryotic organisms that include molds, yeasts, and mushrooms.

Question 64

Which eukaryotic kingdom does **yeast** belong to?

Answer 64

Fungi ## Footnote They are unicellular fungi that play crucial roles in fermentation and can be found in various environments.

Question 65

# Fill in the blank: Fungi reproduce **both** sexually and \_\_\_\_\_\_\_\_.

Answer 65

Asexually ## Footnote Fungi can reproduce through *spores*, which can be produced either sexually or asexually, depending on the species.

Question 66

# Define: eukaryotic cell

Answer 66

A cell with a **defined nucleus**. ## Footnote Organisms with eukaryotic cells are referred to as *eukaryotes*. These include all animals, plants, fungi, seaweeds, and other organisms.

Question 67

# Define: prokaryotic cell

Answer 67

A cell **without** a nucelus or membrane-bound organelles. ## Footnote Organisms with these cells are called *prokaryotes*. This includes bacteria and archea. These cells are often smaller and more simple.

Question 68

# Define: organelles

Answer 68

A **subcellular structure** that completes a specific job within a cell. ## Footnote They can be membrane-bound (surrounded by a lipid bilayer) or non-membrane bounded. The structure and function of these units varies depending on the type of cell.

Question 69

What are the three kinds of **multicellular eukaryotes?**

Answer 69

1. Plants 2. Animals 3. Fungi ## Footnote *Protists* are considered eukaryotes, but they are generally unicellular.

Question 70

What are the **four levels of organization** within a living organism?

Answer 70

1. Cell 2. Tissue 3. Organs 4. Organ System ## Footnote The organ system is the highest level of organization, and is made up of multiple organs, which are made up of tissues, which is made up of cells.

Question 71

# Define: homeostasis

Answer 71

The process of **maintaining** a stable internal environment. ## Footnote Examples include regulating *body temperature*, *blood sugar*, and *hydration levels* to keep the body functioning properly.

Question 72

# True or False: Sweating helps **maintain** homeostasis.

Answer 72

True ## Footnote **Sweating** cools the body by releasing heat, preventing overheating and helping maintain a stable body temperature.