Living Organisms

Unit Review Sheet

Facts and Definitions

Lesson 1: Levels of Organization

• Structure refers to how an organism is physically or biologically organized.
• Functions are things that an organism is able to do.
• Behavior is how an organism acts or responds.
• In a living organism, the levels of organization are cells —> tissues —> organs —> organ systems —> organisms.

Lesson 2: Structure and Stability

• An adaptation is a beneficial change in an organism that allows the organism to survive in its environment.
• Adaptations can be modifications to an organism's structure, function, or behavior.

Lesson 3: Plant Reproduction

• Fitness is an organism's ability to survive and reproduce
• Gametes are male and female reproductive cells.
• Pollen is a powdery substance that contains male gametes.
• Ovules are structures that contain female gametes; a fertilized ovule develops into a seed.
• An embryo is an undeveloped plant found in a seed.
• Endosperm is the food for the developing embryo.
• Germination is the process where seeds sprout and begin to grow.
• The plumule is located at the tip of the epicotyl in the embryo; it will become the bud part of the plant.
• The epicotyl is the part of the embryo that develops into the shoot of the plant (the part above ground).
• The hypocotyl is the section of the embryo that attaches to the cotyledons.
• The radicle is the bottom part of the hypocotyl in the embryo; this section develops into the plant's root.
• The cotyledons are the part of the embryo that contains the endosperm; these will develop into leaf-like parts of the shoot.
• The testa is the outer coat of the seeds; it protects the embryo from damage.

Lesson 4: Biotic and Abiotic Factors

• Biotic factors are influences that come from other living organisms such as animals, fungi, plants, or even humans.
• Abiotic factors are nonliving, inanimate factors such as light, temperature, soil type, water, and energy.

Lesson 5: Nutrition

• Nutrition describes the process in which all living organisms intake and use food.
• Autotrophs are organisms, like plants, that can make their own food.
• Heterotrophs are organisms that must consume other living things (such as plants or animals) in order to obtain food.
• Photosynthesis is the process by which plants and some other autotrophs generate carbohydrates and oxygen from carbon dioxide, water, and sunlight.
• The formula for photosynthesis is 6 CO₂ + 6 H₂0 + ENERGY —> C₆H₁₂O₆ + 6 O₂
• Digestion is the process of breaking food down so the body can absorb the food's nutrients.
• In a monogastric digestive system, an animal has one stomach that has only one section or chamber.
• The ruminant digestive system has a four-chambered stomach, and animals must regurgitate and chew fermented portions of their food, called cud.
• Animals with a pseudo-ruminant digestive system have a three-chambered stomach.
• Most birds have an avian digestive system featuring a holding area called a crop and a muscular organ (gizzard) that helps "chew" the food.

Lesson 6: Respiration

• Respiration is a chemical reaction inside an organism's cells that combines nutrients (food) and oxygen (in most cases) to create energy.
• In most cells, respiration involves a process of converting sugar (glucose) to ATP (adenosine triphosphate), an energy storage unit for cells.
• With anaerobic respiration, a cell or organism can convert food to energy in the absence of oxygen.

Lesson 7: Stimulus and Response

• A stimulus is something external that influences activity or responses.
• Taxis occurs when a mobile organism instinctively moves toward or away from a stimulus.
• Tropism occurs when an organism, most often a plant, bends or turns toward or away from a stimulus.

Lesson 8: Behavior

• Conditioning means learning a response that differs from the natural one.
• Spatial learning is the process of learning and memorizing information about location and orientation.
• Trial-and-error learning is when an animal learns what to do or what not to do based on prior successes or failures.
• Imitation is when an animal learns by observing another animal's behavior and then imitating that behavior.
• Imprinting occurs after the birth of some animals where they "learn" that the first thing they see is their mother.
• Habituation is a process where an animal decreases or stops a natural response due to repeated exposure to a stimulus.
• Sensitization occurs when an animal increases a natural response due to earlier experiences, often negative experiences.

Lesson 9: Ecological Relationships

• Parasitism is a relationship between two different kinds of organisms in which one (the parasite) receives benefits from the other (the host) while causing damage to it (usually not fatal damage).
• Commensalism is a relationship between two different kinds of organisms when one receives benefits from the other without affecting it.
• Mutualism is a relationship between two different species of organisms that are interdependent; each gains benefits from the other.
• Predation is a relationship between two different organisms where one organism (predator) kills the other organism (prey) for food.
• Coexistence is the state of two or more things existing together, with or without mutual interaction.
• Competition is the struggle amongst organisms, both of the same and different species, for the same space, food, and other requirements.
• Symbiosis is when two different organisms interact, usually over an extended period of time.

Lesson 10: Structural Similarities

• A cladogram is a branching treelike diagram representing relationships among organisms.

Final Project: Exploring Living Organisms

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