Characteristics of Living Things and Atomic Structure

This page delves into the fundamental characteristics of living organisms and the basic structure of atoms.

Characteristics of living things include:

1. Growing and developing
2. Possessing DNA
3. Being composed of cells
4. Obtaining and using energy
5. Maintaining a stable internal environment
6. Reproducing
7. Evolving
8. Responding to the environment

Highlight: These characteristics collectively define what it means to be "alive" in biological terms.

The page then explores atomic structure:

• Protons: Positive charge, found in nucleus
• Neutrons: No charge, found in nucleus
• Electrons: Negative charge, found outside nucleus in electron cloud

Vocabulary: An isotope is an atom of the same element but with a different number of neutrons.

The composition of water molecules is explained: 2 hydrogen atoms and 1 oxygen atom.

The page distinguishes between covalent and ionic bonds:

Definition: Ionic bonds involve the transfer of electrons from one atom to another, while covalent bonds involve the sharing of electrons between atoms.

Chemical Bonding and Water Properties

This section focuses on the importance of carbon in biological systems and the unique properties of water.

Carbon's significance in biology is highlighted:

Highlight: Carbon is crucial because it can form many kinds of bonds and create essential compounds for life.

The page explains ion formation:

• Positive ions form when atoms lose electrons
• Negative ions form when atoms gain electrons

Water's polarity is described:

Definition: Water is polar due to unevenly distributed charges, with the negative charge near the oxygen atom and positive charges near the hydrogen atoms.

The difference between solvent and solute is clarified:

• Solute: The substance being dissolved $e.g., sugar$
• Solvent: The substance in which the solute dissolves $e.g., water$

The role of enzymes in biological reactions is explained:

Vocabulary: Enzymes are biological catalysts that decrease the activation energy of a reaction, thereby increasing its speed.

Definition: Activation energy is the energy needed to initiate a reaction.

Chemical Reactions and Levels of Ecological Organization

This page covers chemical reactions in biology and the hierarchical organization of ecological systems.

A simple chemical reaction is presented:

CO₂ + H₂O → H₂CO₃

Example: This reaction represents the formation of carbonic acid, which is important in maintaining pH balance in blood.

The levels of ecological organization are explained, from smallest to largest:

1. Organism: An individual living thing
2. Population: A group of individuals of the same species in a defined area
3. Community: Several interacting populations living together
4. Ecosystem: All organisms in an area plus their physical environment
5. Biome: A group of ecosystems with similar climates and typical organisms
6. Biosphere: All life on Earth and the areas where life exists

Highlight: Understanding these levels is crucial for comprehending the interconnectedness of living systems.

The page also introduces producers and consumers:

Vocabulary: Producers $autotrophs$ create their own food, while consumers $heterotrophs$ obtain energy by consuming other organisms or organic matter.

Energy Flow in Ecosystems

The final page focuses on energy flow through ecosystems and food webs.

Producers $autotrophs$ are described in detail:

Definition: Producers are organisms that can create their own food, primarily through photosynthesis or chemosynthesis.

Examples of producers include plants, some bacteria, and algae.

The difference between food chains and food webs is explained:

Highlight: A food chain shows a single path of energy transfer, while a food web represents all interconnected food chains in an ecosystem.

The page emphasizes the importance of each organism in an ecosystem:

Example: If an organism is removed from a food chain, it affects all other organisms in the ecosystem, demonstrating the delicate balance of nature.

Energy transfer efficiency in food chains is discussed:

Highlight: Only about 10% of energy is transferred from one trophic level to the next in a food chain.

This comprehensive guide provides students with a solid foundation in key biology midterm concepts, from the scientific method to ecosystem dynamics.

Page 5: Energy Flow in Ecosystems

This page examines energy transfer through food chains and food webs in ecosystems.

Definition: A food chain shows energy transfer through organisms eating and being eaten.

Highlight: Only 10% of energy transfers between trophic levels in a food chain.

Example: Producers include plants, bacteria, and algae, forming the base of food chains.

Page 6: Symbiotic Relationships

This section explores different types of symbiotic relationships between organisms.

Definition: Symbiosis refers to two species living in close association with one another.

Example: Mutualism occurs when both species benefit, such as the relationship between zooplankton and whales.

Vocabulary: Commensalism is when one species benefits while the other is neither harmed nor helped.

Page 7: Cell Transport and DNA

This page covers cellular transport mechanisms and DNA structure.

Definition: An isotonic solution has the same osmotic pressure as another solution.

Vocabulary: Hypotonic solutions have lower osmotic pressure, while hypertonic solutions have higher osmotic pressure.

Highlight: Chargaff's rule describes the ratio of DNA bases in organisms.

Scientific Method and Basic Concepts

The first page introduces fundamental scientific concepts and measurement principles crucial for biology studies.

The scientific method is defined as an organized way of gathering and analyzing evidence about the natural world. It involves several key steps:

1. Observe and ask questions
2. Make inferences and form hypotheses
3. Conduct controlled experiments, collect and analyze data
4. Draw conclusions

Definition: A hypothesis is a testable explanation for an observed phenomenon.

The page explains the difference between independent and dependent variables in experiments:

Highlight: The independent variable is deliberately changed, while the dependent variable is observed and changes in response to the independent variable.

Basic units of measurement are introduced, with the meter being the basic unit of length.

The pH scale is also covered:

• Acidic pH range: 0-7 $0 being most acidic$
• Basic pH range: 7-14 $14 being most basic$
• Neutral pH: 7

Example: The pH scale is crucial for understanding chemical reactions in biological systems. For instance, stomach acid typically has a pH of 1-2, while blood has a pH of about 7.4.