Criteria of Life and Carbon-Based Organisms

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Questions and Answers

What are the key criteria that define living organisms?

The key criteria include growth, reproduction, response to stimuli, and metabolism.

Why is carbon important for life?

Carbon is essential because all organic molecules, which are fundamental for life, are carbon-based.

How do phenotypes relate to natural selection?

Phenotypes are observable traits that influence an organism's chances of survival and reproduction, thereby driving natural selection.

What are the two main types of metabolic processes?

The two main types are catabolism, which breaks down molecules to release energy, and anabolism, which builds molecules using energy. Signup and view all the answers

What role does water play in chemical reactions within an organism?

Water is crucial in hydrolysis, which breaks down molecules, and in dehydration, which builds molecules. Signup and view all the answers

What is the purpose of photosynthesis?

The purpose of photosynthesis is to convert sunlight into chemical energy in the form of glucose and produce oxygen. Signup and view all the answers

Describe the process of cellular respiration.

Cellular respiration is the process where organisms break down glucose in the presence of oxygen to release energy. Signup and view all the answers

What is a photopigment and its role in photosynthesis?

A photopigment, such as chlorophyll, absorbs light energy which is necessary for photosynthesis. Signup and view all the answers

What is the role of photolysis in photosynthesis?

Photolysis is the process where water is split by light to produce oxygen, which is a byproduct of photosynthesis. Signup and view all the answers

How do photosynthesis and cellular respiration complement each other in an ecosystem?

Photosynthesis captures and stores energy in glucose, while cellular respiration releases that energy for use, producing carbon dioxide as a byproduct. Signup and view all the answers

Define autotrophs and provide an example.

Autotrophs are organisms that produce their own food through photosynthesis; an example is a plant. Signup and view all the answers

Why is energy continually replenished from the sun in an ecosystem?

Energy needs to be replenished because it is lost as heat during every energy transfer within the ecosystem. Signup and view all the answers

What is the function of decomposers in an ecosystem?

Decomposers break down dead organisms, recycling nutrients back into the ecosystem. Signup and view all the answers

What distinguishes an omnivore from herbivores and carnivores?

Omnivores eat both plants and animals, while herbivores eat only plants and carnivores eat only animals. Signup and view all the answers

What is the purpose of having controlled variables in an experiment?

Controlled variables ensure that the experiment tests only the effect of the independent variable by keeping other factors constant. Signup and view all the answers

Explain the significance of oxygen in cellular respiration.

Oxygen is essential as it acts as the final electron acceptor, allowing for the efficient production of ATP during cellular respiration. Signup and view all the answers

Study Notes

Criteria of Life and Survival

All living organisms share common characteristics, known as the criteria of life.
These criteria enable organisms to survive and adapt to their environment.
Growth: Organisms increase in size and complexity.
Reproduction: The ability to produce offspring to continue the species.
Response to stimuli: Organisms react to environmental changes.
Metabolism: All chemical processes that sustain life.

Carbon-Based Life

All life forms are made of organic molecules, which contain carbon and hydrogen.
These molecules are essential for life.
Humans are composed of four main types of organic molecules:
- Proteins: Provide structure, support, and carry out various functions.
- Lipids: Include fats, oils, and waxes, providing energy storage and insulation.
- Carbohydrates: Provide energy sources like sugars and starches.
- Nucleic acids: Carry genetic information, like DNA and RNA.

Phenotype, Adaptation, and Natural Selection

Phenotype: The observable traits or characteristics of an organism.
Phenotypes play a crucial role in adaptation:
- Organisms with beneficial phenotypes, traits that help them survive and reproduce in their environment, are more likely to pass on their genes.
- Over time, natural selection favors these advantageous phenotypes, leading to adaptations within a population.

Metabolism

Metabolism refers to the sum of all chemical reactions in an organism.
Catabolism (breaking down): Releases energy by breaking down complex molecules into simpler ones. Example: Cellular respiration.
Anabolism (building up): Consumes energy to build complex molecules from simpler ones. Example: Protein synthesis.

Water in Chemical Reactions

Water is crucial for both catabolic and anabolic reactions in organisms.
Hydrolysis: Water is used to break down molecules in catabolic reactions.
Dehydration: Water is removed during anabolic reactions to build larger molecules.

Energy Concepts

We eat to obtain energy and nutrients that sustain life.
Organisms use two primary forms of energy:
- Chemical energy: Stored in food molecules, like glucose.
- **Light energy:**Used by plants during photosynthesis.
We breathe to provide oxygen for cellular respiration, which generates ATP (energy currency for cells).

Photosynthesis

Photosynthesis is the process plants use to convert sunlight into chemical energy (glucose) and oxygen.
Equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

Cellular Respiration

Cellular respiration breaks down glucose to release energy.
Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
Energy stored in glucose is transformed into ATP, a high-energy molecule used by cells to perform work.

Photopigment

A photopigment, such as chlorophyll, absorbs light energy necessary for photosynthesis.

Oxygen Production

Oxygen is produced during photolysis, the splitting of water by light in photosynthesis.

Photosynthesis and Cellular Respiration: A Partnership

Photosynthesis captures light energy and stores it as glucose.
Cellular respiration releases energy from glucose, producing ATP and CO₂. These two processes are interconnected.

Ecosystem Structure

Autotroph: Organisms that make their own food through photosynthesis (e.g., plants, algae)
Heterotroph: Organisms that must consume other organisms for food (e.g., animals).
Decomposers: Organisms that break down dead organisms (e.g., fungi and bacteria).
Herbivore: Eats plants.
Carnivore: Eats animals.
Omnivore: Eats both plants and animals.

Role of Photosynthetic Organisms

Plants and phytoplankton are the foundation of ecosystems.
They capture solar energy and convert it into chemical energy (glucose), which sustains all other life forms.

Energy and Matter in Ecosystems

Energy flow: Energy from the sun is continuously needed because it is lost as heat with each energy transfer.
Matter cycling: Matter cycles through ecosystems, being reused by different organisms.

Science and the Scientific Method

Independent variable: The factor intentionally changed in an experiment.
Dependent variable: The factor that is measured or observed in response to the change in the independent variable.
Controlled variables: Factors kept constant during an experiment to isolate the effect of the independent variable.

Control in Experiments

A control acts as a standard for comparison to determine the effect of the independent variable.

Formulating a Hypothesis

Hypothesis: A testable statement predicting the outcome of an experiment.

Interpreting Graphs

The ability to understand and analyze data presented in graphical form is essential in scientific investigations.

Additional Notes

Oxygen and Respiration: Oxygen acts as the final electron acceptor in cellular respiration. Electrons and hydrogen ions combine with oxygen to form water, releasing energy.
Photosynthesis and Energy Storage: Light energy is captured by chlorophyll, converted into chemical energy in glucose, and subsequently used by organisms for energy.

Key Diagrams to Understand

Energy flow through ecosystems: Solar energy enters ecosystems via photosynthesis.
Energy transfer through food chains: Energy is transferred between organisms in a food chain, and a portion is released as heat during cellular respiration.

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Description

This quiz explores the fundamental criteria of life that all living organisms share, including growth, reproduction, response to stimuli, and metabolism. It also delves into the importance of carbon-based molecules essential for life, such as proteins, lipids, carbohydrates, and nucleic acids. Test your understanding of these key concepts in biology!