Biology 20 Final Exam Review

This review encompasses essential biological concepts, terminology, and processes necessary for an understanding of Biology 20. The following sections address key themes, diagrams, and critical processes.

Key Terminology

Biosphere: All areas on Earth capable of sustaining life, including air, water, and land.
Equilibrium: The balance within a system where fluctuations cancel out, resulting in no net change over time.
Producers: Organisms that produce their own food, utilizing chemical or solar energy; also known as autotrophs.
Consumers: Organisms that obtain food by consuming other organisms; categorized as heterotrophs.
Decomposers: Organisms that break down dead or decaying matter to obtain nutrients.
Niche: The role of a population or individual within its ecosystem.
Ecosystem: A community of living organisms alongside abiotic factors interacting within a specific environment.
Homeostasis: The process of maintaining a constant internal environment in the body despite external changes, relying on feedback systems for regulation.
Biome: Major regional biotic communities characterized by dominant plant life and climate, including diverse habitats such as grasslands and deserts.
Habitat: The environmental area where an organism or ecological community lives.
Range: The geographic availability of a species.
Carbon Sink: Natural environments that absorb more carbon dioxide from the atmosphere than they release.

Diagrams to Review

Diagram of the three domains of life: Archaea, Bacteria, and Eukarya.
Food Chains and Trophic Levels: Energy is diminished at each level of a food chain, with less than 10% energy transfer between levels, generally limiting ecosystems to five trophic levels.

Food Chains and Energy Transfer

The concept of trophic levels illustrates how energy and matter circulate within ecosystems, represented visually in pyramids of energy and biomass. A pyramid of energy shows the decreasing energy available at successive levels of the food chain, while a pyramid of biomass indicates the amount of living material at each level, decreasing as one moves upward.

Photosynthesis and Chemosynthesis

Photosynthesis is the process utilized by plants, algae, and specific bacteria to convert solar energy into chemical energy, forming carbohydrates like glucose. The chemical equation for photosynthesis is essential to understand in terms of input (water and carbon dioxide) and output (glucose and oxygen).

Chemosynthesis occurs in environments devoid of sunlight, where certain bacteria and fungi convert inorganic carbon into carbohydrates using chemical energy from nutrients. Understanding both processes emphasizes the different ways organisms convert energy in their environments.

Food Webs vs. Food Chains

Food Chain: A linear pathway showcasing how organisms consume one another.
Food Web: A complex network illustrating multiple interconnections between various food chains, emphasizing the ecosystem's interconnectedness.

Biomagnification

Biomagnification refers to the increasing concentration of toxic substances, such as pesticides, in organisms at higher trophic levels. For example, if insects accumulate a pesticide, a lizard consuming them will ingest far more of the toxin, and this concentration increases with predators further up the food chain.

Nitrogen Cycle

The nitrogen cycle describes the movement and transformation of nitrogen within the environment: Nitrogen (N₂) from the atmosphere is converted by lightning or nitrogen-fixing bacteria into usable forms (ions), which are absorbed by plants. The cycle involves processes like ammonification, assimilation by herbivores, and eventual return to the atmosphere through denitrification.

Water's Properties and Evolution

Water possesses unique physical properties, being the only substance present in all three states at normal Earth temperatures, having high surface tension due to molecular cohesion and adhesion, and facilitating capillary action, which is crucial for nutrient transport in plants.

Evolution is defined as the gradual change in heritable traits in populations over generations, while adaptation describes adjustments in organisms that enhance survival in specific environments. Historical figures like Lamarck and Darwin contributed significantly to evolutionary theory, presenting differing views on traits and natural selection.

Cellular Respiration

The process of cellular respiration converts glucose into ATP, the energy currency of cells. In aerobic respiration, one glucose molecule yields about 36 ATP, while fermentation only produces two ATP. Muscle cells shift from aerobic to anaerobic respiration during intense activity due to oxygen scarcity, resulting in lactic acid buildup and subsequent discomfort.

Digestive System Overview

Accessory Organs: The pancreas produces enzymes for digestion and regulates blood sugar; the liver produces bile for fat emulsification and detoxifies blood; the gall bladder stores bile.
Mouth: Initiates digestion through mechanical and chemical processes.
Stomach: Further breaks down food using gastric juices, converting it to chyme.
Small Intestine: The primary site for digestion and absorption; includes duodenum, jejunum, and ileum sections.
Large Intestine: Extracts water and forms feces.

Cardiovascular and Blood Components

The heart functions as a pump, circulating oxygen-rich and deoxygenated blood through a coordinated pathway. The composition of blood includes red blood cells for oxygen transport, white blood cells for immune response, platelets for clotting, and plasma for nutrient and waste transport.

Urinary System and Nephron Function

The kidneys filter blood to produce urine, regulating blood pressure through the reabsorption of sodium and water. Nephrons, the functional units of the kidneys, operate via filtration, reabsorption, and secretion, ensuring balance and homeostasis.

Respiratory System Mechanics

Air enters through the trachea, branching off into bronchi leading to the alveoli, where gas exchange occurs via diffusion. Breathing regulation is autonomic and managed by the brain detecting carbon dioxide and oxygen levels in the blood.

Muscle Contraction and Types

Muscle contraction involves interaction between actin and myosin filaments, using ATP as energy. Key muscle types include smooth, cardiac, and skeletal muscles, each with distinct functional characteristics. Skeletal muscles work in pairs to create movement by pulling on bones.

Conclusion and Additional Considerations

This review encapsulates fundamental biological concepts crucial for mastery of Biology 20 topics. Students are encouraged to explore related themes for deeper understanding and retention.

Biology 20 Final Exam Comprehensive Review

Biology 20 Final Exam Comprehensive Review