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Life On Earth Unit Overview

Unit Summary

 

We start the 7th grade curriculum looking at the questions of what it means to be alive and how living things survive. We start on the small scale - investigating microorganisms and designing/building a sustainable growing system for plants. 

The first part of the unit (what does it mean to be alive?) explores how we know that things are living, classification schemes for living things, and what living things need to survive. The second part of the unit (how do living things survive?) explores  cell structures, cell processes, how organisms interact, and genetics.  


Big Ideas

 

Cells

 

  • All living things are made up of cells
  • Cells come in many different shapes and sizes but they all share basic parts and processes


Characteristics of Life

 

  • Living things are made up of parts that work together
  • All cells and organisms have the same basic needs.
  • There are common needs that all living things share
  • Different organisms require different resources
  • In classifying organisms, scientists consider details of both internal and external structures
  • Traditionally, a species has been defined as all organisms that can mate with one another to produce fertile offspring. 5A/M4*  
  • Organisms get energy from oxidizing their food, releasing some of their energy as heat.
  • Food provides molecules that serve as fuel and building materials for all organisms.


Flow of Matter & Energy in the Biosphere

 

  • Almost all Earth’s life depends on photosynthesis.
  • Plants get energy directly, using sunlight, carbon dioxide, and water to make the food they need.
  • Animals (including us) get energy indirectly, eating both plants and other animals to get the food they need.
  • Many materials can be recycled (both in nature and in human societies) and used again, sometimes in different forms.
  • One organism may scavenge or decompose another.
  • The cycles continue indefinitely because organisms are decomposed after death to return food materials to the environment
  • Over a long time, matter is transferred from one organism to another repeatedly and between organisms and their physical environment. As in all material systems, the total amount of matter remains constant, even though its form and location change.
  • The atmosphere is a mixture of nitrogen, oxygen, traces amounts of water vapor, carbon dioxide and other gases
  • Organisms play specific and important roles in ecosystems (such as decomposers, producers, consumers)
  • Materials can be constantly cycled and recycled through an ecosystem
  • An individual’s lifestyle has a measurable impact on an ecosystem (Ecological Footprint)
  • Some methods of growing food are more or less sustainable.


Evolution & Adaptations

 

  • Some organisms survive from the beginning of life on Earth with little or no change, many die out altogether and others change repeatedly, sometimes giving rise to more complex organisms
  • Organisms with traits best suited to their environments are more likely to survive and reproduce
  • Inherited characteristics may change over time as adaptations to changes in the environment
  • Changes in environmental conditions can affect survival of individual organisms or entire species

 

 

Content Learning Expectations


Characteristics of Life and Cells

 

  • Explain how a cell is a system, how the parts of the system work together, and how the cell is part of other systems
  • Explain how a cell’s structure is determined by its function
  • Explain that the needs of all organisms are met at the cellular level
  • Energy and matter are processed at the cellular level and can be used immediately or stored for future use
  • Create a cell analogy model
  • Design and create a visual representation (e.g., model, book, video,) of how a cell is a system
  • Demonstrate the classification of organism using a generally accepted classification system 



Matter

 

  •  Create a visualization of the carbon cycle and nitrogen cycle
  •  Describe how atoms and molecules are the building blocks of matter (e.g., cell parts, nutrients,minerals)
  •  Identify and/or describe the elements that are most common in both living and nonliving things on Earth
  • Design a working model of the transfer of matter and energy through a system that includes living and nonliving things (Sustainable Living and decomposition column)
  • Compare and contrast photosynthesis and respiration


Energy


      •  Describe how matter and energy change from one form to another in living things and in the
          physical environment
      •  Give evidence to show that the total amount of matter in the environment stays the same even as
          its form and location change
      
Ecology and Environmental Science

 

  • Describe how matter and energy change from one form to another in living things and in the physical environment
  • Give evidence to show that the total amount of matter in the environment stays the same even as its form and location change
  • Explain how producers (plants that contain chlorophyll) use energy from sunlight, carbon dioxide, and water to make sugars through a process called photosynthesis. Recognize that this food can be used immediately, stored for later use or used by other organisms. (MA)
  • Compare and contrast photosynthesis and respiration.
  • Model how dead plants and animals are broken down by other living organisms
  • and how this process contributes to matter cycling and energy transfer (MA) [Bottle biology]
  • Design and construct a system to show how organisms depend on the carbon, nitrogen and water cycles. [sustainable growing project]


Evolution

 

  • Analyze how an organism’s traits and structures (e.g., mouthparts, leaves) perform functions that allow it to reproduce and survive in an ecosystem (MA)
  • Describe how small differences between parents and offspring can lead to descendants who are very different from their ancestors over many generations
  • Compare changes of a specific characteristic of a population across multiple generations (e.g., the skull size of humans, bird beaks, articulated appendages)
  • Describe how variations in the behavior and traits of an offspring may permit some of them to survive a changing environment
  • Formulate a hypothesis to explain the extinction of particular species using information about specific adaptations, environmental changes, and/or human activity (MA)
  • Use evidence drawn from geology, fossils, and comparative anatomy to support the theory of evolution (MA)



Adaptation & Biodiversity

 

  • Recognize that genes (located in the chromosomes) contain hereditary information that provide instructions for building proteins (and specifying the physical characteristics (traits) of an organism (MA)
  • Explain how genes and chromosomes are passed on from generation to generation during cell division (MA)
  • Compare sexual reproduction (offspring inherit half of their genes from each parent) with asexual reproduction (offspring are identical copies of the parent cell) (MA)
  • Recognize that a mutation in a gene can result a new trait which may be helpful, neutral or harmful.



Engineering (Sustainability Project)

 

  • Apply the Engineering Design Process to (a) create a simple sustainable food growing system, and (b) create a simple way of composting
  • Evaluate how sustainable a food growing system is.
  • Describe pros and cons of local vs. non-local food production.
  • Identify the common needs of all living things.
  • Identify the different needs of different organisms.
  • Identify the roles that different organisms play in a sustainable system.
  • Describe the roles that different organisms play in cycling specific materials through a system.
  • Describe the Water, Carbon, and Nitrogen Cycles.
  • Describe specifically how each of the three nutrients are cycled through a system.
  • Understand what contributes to an individual’s “Ecological Footprint”, and ways to reduce that
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