Study sheet: Introduction to Biology

📋 Course Outline

1. Biology and Its Major Themes
2. Cellular Organization and Information
3. Reproduction Evolution and Ecology
4. Energy Matter and Nutrition
5. Characteristics of Living Things
6. Scientific Method and Evidence
7. Microscopes and Measurement

📖 1. Biology and Its Major Themes

🔑 Key Concepts & Definitions

• Biology : the study of life and the science of living things

★ Must-know

• Life arose more than 3.5 billion years ago, and the first organisms were single-celled.

• The major themes of biology are:

  • cell structure and function
  • stability and homeostasis
  • reproduction and inheritance
  • evolution
  • interdependence of organisms
  • matter, energy, and organization

Further detail

• The word biology comes from bios, meaning life, and logos, meaning study.

💡 Memory Hook

Life themes: cells, stability, reproduction, evolution, interdependence, and energy

📖 2. Cellular Organization and Information

🔑 Key Concepts & Definitions

• Cell : the basic unit of life, and all organisms are made of and develop from cells

📝 Essential Points

📌 Unicellular organisms consist of one cell, whereas multicellular organisms consist of two or more cells.

• All cells are surrounded by a plasma membrane and contain DNA, while specialized organelles carry out particular life processes.

• 🔄 Organization in multicellular organisms proceeds through:

  1. cells
  2. tissues
  3. organs
  4. systems
  5. organism

💡 Memory Hook

Cells → tissues → organs → systems → organism

📖 3. Reproduction Evolution and Ecology

🔑 Key Concepts & Definitions

• Homeostasis : the maintenance of stable internal conditions such as temperature, water content, and chemical content
• Natural selection : the process in which organisms with favorable traits reproduce more successfully, causing populations to change over generations
• Ecology : the interaction of organisms with one another and with their environment

★ Must-know

📌 Sexual reproduction combines hereditary information from two organisms of the same species, whereas asexual reproduction uses hereditary information from one organism.

Further detail

• In sexual reproduction, an egg and sperm form a zygote containing hereditary information from both parents.

💡 Memory Hook

Sexual reproduction combines two parents, whereas asexual reproduction uses one parent

📖 4. Energy Matter and Nutrition

🔑 Key Concepts & Definitions

• Autotrophs : organisms that make their own food; phototrophs use solar energy through photosynthesis, while chemotrophs use chemical processes
• Heterotrophs : organisms that must take in food to meet their energy needs

★ Must-know

• All energy comes from the Sun directly or indirectly, and photosynthesis transforms solar energy into chemical energy usable by living things.

Further detail

• In photosynthesis, phototrophs convert $H_2O$ and $CO_2$ into sugar and $O_2$.

• Heterotrophs may consume autotrophs as herbivores, other heterotrophs as carnivores, or both as omnivores.

💡 Memory Hook

Sunlight or chemical energy → autotrophs → heterotrophs → organized living processes

📖 5. Characteristics of Living Things

🔑 Key Concepts & Definitions

• Metabolism : the sum of all chemical processes in an organism, including digestion and absorption

★ Must-know

• Growth results from cell division and cell enlargement, and cell division forms two cells from a preexisting cell.

• Reproduction is not essential for the survival of an individual but is essential for continuation of a species.

Further detail

• 🔄 Development proceeds through:

  1. repeated cell divisions
  2. cell differentiation
  3. formation of an adult organism

• Living things respond to external stimuli such as light, heat, sound, and chemical or mechanical contact.

💡 Memory Hook

Energy use, homeostasis, growth, development, reproduction, response, evolution, movement

📖 6. Scientific Method and Evidence

🔑 Key Concepts & Definitions

• Hypothesis : a testable statement made in advance about the results expected from testing, often written as an if-then statement

★ Must-know

• 🔄 The scientific method proceeds by:
  1. observation
  2. asking a question
  3. forming a hypothesis
  4. experimenting
  5. organizing and analyzing data
  6. drawing a conclusion
  7. communicating results

📌 In a controlled experiment, the control and experimental groups are identical except for the independent variable, and the dependent variable is measured in both groups.

📌 A theory is a broad statement supported by considerable evidence and tying together related hypotheses, whereas a law is a concise statement of fact that may be expressed as a mathematical equation.

Further detail

• Scientists communicate findings through journals and scientific meetings so that other scientists can examine, verify, and build on the work.

💡 Memory Hook

Observe → question → hypothesize → experiment → analyze → conclude → communicate

📖 7. Microscopes and Measurement

🔑 Key Concepts & Definitions

• Magnification : the increase in the apparent size of an object produced by a microscope
• Resolution : the ability of a microscope to show details clearly

★ Must-know

📐 Formula — For a compound light microscope, total magnification equals the eyepiece power multiplied by the objective power, such as $10X \times 40X = 400X$.

📌 A transmission electron microscope produces an image of a very thin specimen and reaches 200,000X magnification, whereas a scanning electron microscope produces a three-dimensional surface image and reaches 100,000X magnification.

Further detail

• A compound light microscope uses ocular and objective lenses, requires a thin or very small specimen, and can be used to study living specimens.

💡 Memory Hook

Light microscopes can view living specimens, whereas electron microscopes cannot

📊 Synthesis Tables

Microscope Comparison

Microscope	Image and specimen	Magnification and living specimens
Compound light microscope	Thin or very small specimen; lens-based image	Around 1000X; living specimens possible
TEM	Very thin specimen; image on screen or photographic plate	200,000X; living specimens impossible
SEM	Uncut, metal-coated surface; three-dimensional image	100,000X; living specimens impossible