Biology Chapter 1: Introduction to Biology

Questions and Answers

What is a key difference between RNA and DNA?

RNA is single-stranded and involved in protein synthesis. (correct)

RNA stores genetic information long-term while DNA is more versatile.

DNA is more versatile and involved in protein synthesis.

DNA is single-stranded while RNA is double-stranded.

Which of the following is NOT a type of carbohydrate?

Glucose

Glycogen

Sucrose

Triglyceride (correct)

What property allows membranes to maintain homeostasis?

Active Transport

Osmosis

Fluid Mosaic Model

Selective Permeability (correct)

Which process does NOT require energy?

Facilitated Diffusion Signup and view all the answers

What is the primary building block of proteins?

Amino acids Signup and view all the answers

What do eukaryotic cells have that prokaryotic cells do not?

Nucleus Signup and view all the answers

What is the main function of ribosomes?

Protein synthesis Signup and view all the answers

What is the secondary structure of a protein characterized by?

Alpha helices and beta sheets Signup and view all the answers

Which type of bond in carbohydrates stores potential energy?

Covalent bond Signup and view all the answers

How does denaturation affect a protein?

It leads to loss of structure and function. Signup and view all the answers

Which nucleotides base pair correctly in DNA?

Adenine - Thymine Signup and view all the answers

What characteristic defines the structure of the plasma membrane?

Fluid Mosaic Model Signup and view all the answers

What is the sugar-phosphate backbone of nucleic acids composed of?

Alternating sugar and phosphate groups Signup and view all the answers

What role do enzymes play in biochemical reactions?

They lower activation energy. Signup and view all the answers

Which statement accurately describes RNA?

RNA can serve as a template for protein synthesis. Signup and view all the answers

What characteristic distinguishes hydrophilic substances from hydrophobic substances?

Hydrophilic substances interact with water. Signup and view all the answers

Which of the following is NOT one of the five criteria for life?

Respiration Signup and view all the answers

What does the Central Dogma of molecular biology describe?

The flow of genetic information within a biological system Signup and view all the answers

In the context of scientific experiments, what is the purpose of a null hypothesis?

To assert that there is no effect or difference Signup and view all the answers

Which of the following correctly represents the classification hierarchy from smallest to largest?

Atoms → Molecules → Organelles → Cells Signup and view all the answers

Which of the following statements best describes the Three-Domain System of classification?

It categorizes life into Bacteria, Archaea, and Eukarya Signup and view all the answers

Which of the following elements is NOT commonly found in living organisms?

Helium (He) Signup and view all the answers

What role does water play in biological systems?

It plays roles in hydrogen bonding, evaporation, and maintaining pH Signup and view all the answers

What is the pH scale range and what does it signify about solutions?

0 to 14; lower numbers are acidic Signup and view all the answers

Study Notes

Introduction to Biology

Living organisms share five criteria: cellular organization, metabolism, homeostasis, growth and reproduction, and heredity.
Cell Theory states all living organisms are made of cells, which arise from pre-existing cells.
Central Dogma outlines genetic information flow: DNA → RNA → Protein.
A gene is a DNA sequence that encodes proteins.
Theory of Evolution by natural selection involves variation, inheritance, and differential fitness.
Measurement unit: Micron (µm) is one-millionth of a meter; metric units include meters (length), grams (mass), and liters (volume).
Hypothesis: Testable statement; Null Hypothesis indicates no effect or difference.
Scientific Theory: Robust explanation of a natural phenomenon based on evidence.
Hierarchical Organization of life: Atoms → Molecules → Organelles → Cells → Tissues → Organs → Organ Systems → Organisms.
Linnaean binomial nomenclature (Genus species) is used for classification.
Species: Group capable of interbreeding and producing fertile offspring; limitations exist with hybrids and asexual organisms.
Three domains: Bacteria, Archaea, and Eukarya.
Four eukaryotic kingdoms: Protista, Fungi, Plantae, Animalia.
Prokaryotic cells lack a nucleus and membrane-bound organelles; Eukaryotic cells possess both.
Phylogenetic Trees illustrate evolutionary relationships among species.
Biodiversity is essential for ecosystem stability and resilience.

Chemistry of Life

Chemical components include elements, atoms (protons, neutrons, electrons), and types of bonds (hydrogen, ionic, covalent).
The Periodic Table provides information on protons, neutrons, and electrons in elements.
Atomic Structure is modeled with electron shells.
Common elements in biology: C, H, O, N, P, S.
Water's Properties: Involves hydrogen bonding, evaporation, adhesion, cohesion, solvent properties, hydrolysis, and condensation.
pH Scale ranges from 0 to 14; acids have pH below 7, while buffers maintain stable pH within organisms.
Organic Compounds (proteins, nucleic acids, carbohydrates, lipids) contain carbon and are covalently bonded.
Functional Groups: Specific atom groupings conferring distinct chemical properties.
Hydrocarbons consist solely of carbon and hydrogen.

Proteins and Enzymes

Amino acids serve as protein building blocks, differing by their side chains (R group).
Hydrophilic substances interact with water; hydrophobic substances repel it.
Protein Diversity: Proteins differ in size, shape, and function.
Levels of Protein Structure:
- Primary: Amino acid sequence.
- Secondary: Alpha helices and beta sheets.
- Tertiary: Three-dimensional folding.
- Quaternary: Assembly of multiple polypeptide chains.
Protein Folding is crucial for functionality; Denaturation is the loss of structure and function.
Examples include Hemoglobin (oxygen transport) and enzymes (catalysts) that lower activation energy.

Nucleic Acids

Nucleotides are the building blocks: consist of a nitrogenous base, five-carbon sugar, and phosphate groups.
Sugar-Phosphate Backbone: Alternating sugar and phosphate groups form DNA and RNA structure, running from 5’ to 3’ end.
Complementary Base Pairing in DNA: Adenine (A) pairs with Thymine (T), Cytosine (C) pairs with Guanine (G); in RNA, A pairs with Uracil (U).
Genetic Information Storage: DNA encodes information for RNA transcription, which translates to proteins.
RNA Versatility allows various functions: catalysis, gene regulation, and protein synthesis template.
RNA Hypothesis: Proposed as the first genetic material, exhibiting both information storage and catalysis roles.
Differences: DNA is double-stranded, stable; RNA is single-stranded and multifunctional.

Carbohydrates

Building Blocks:
- Monosaccharides: Simple sugars (e.g., glucose, fructose).
- Disaccharides: Two linked monosaccharides (e.g., sucrose, lactose).
- Polysaccharides: Long chains (e.g., starch, glycogen, cellulose).
Functions: Carbohydrates provide energy, energy storage, and structural roles.
Energy stored in carbohydrate bonds can be released when broken down.

Lipids

Types: Include fats, oils, phospholipids, and steroids, crucial for energy storage, insulation, and cell membranes.
Fluid Mosaic Model describes the structure of plasma membranes composed of phospholipids, cholesterol, and proteins.
Selective Permeability: Membranes regulate substance passage to maintain homeostasis.
Osmosis: Water movement across a semi-permeable membrane from low solute to high solute concentration.
Transport Mechanisms:
- Simple Diffusion: Molecules move from high to low concentration without energy.
- Facilitated Diffusion: Movement via membrane proteins, also without energy.
- Active Transport: Movement against concentration gradient using energy (ATP).

Cell Structure and Function

Cell Size: Small size promotes efficient nutrient uptake and waste removal.
Compartmentalization: Organelles enable specialized cellular functions, absent in bacteria.
Differences highlight Eukaryotic cells (nucleus and organelles) vs. Prokaryotic cells (lack nucleus and organelles).
Organelles and Functions:
- Ribosomes: Site of protein synthesis.
- Nucleus: Contains DNA and regulates transport via nuclear membrane pores.
- Chromosomes/Chromatin: DNA-protein complexes in the nucleus.

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This quiz covers the foundational criteria for life and major unifying theories in biology, such as the Cell Theory and Central Dogma. Test your understanding of how living organisms are structured and how genetic information is processed. Perfect for students beginning their journey in biological sciences.