Student Portal


Investigation 3 – PreLab









Molecular plant geneticists track down genes to discover their functions and identify genes useful for creating improved plants. Their goal is to improve the production and quality of food and fiber. The genes they identify can be used in different ways, sometimes to create traits completely new to the species and other times to enhance traits that plants already have.


This Investigation is designed to help you to answer the following Focus Questions:

  • What is the importance of light in photosynthesis? 
  • In which parts of the plant does photosynthesis occur? 

Note: These questions are located in your SDR at the beginning and end of the Investigation.



As a class, read the Background(s) in the Investigation. When finished, discuss the following concepts as a class:

  • Green plants and other organisms carry out photosynthesis.
  • They use the energy of light and convert it to chemical bond energy of the sugars that are produced.
  • The chemical equation for photosynthesis is:

  • Plants use the chemical bond energy of the sugars as an energy source. This energy allows them to live and grow.
  • When animals eat plants, the bond energy is used in the same way.
  • Light from the Sun is needed for plants and other organisms to carry out photosynthesis. Without light, photosynthesis cannot occur.
  • Plants are made of different structures. Two of the main structures are the stem and the leaf. These are in turn made of smaller parts called cells.
  • One part of the cell which is important to photosynthesis is the chloroplasts.
  • Chloroplasts are located within a cell and contain chlorophyll.
  • Chlorophyll is the green pigment needed for photosynthesis.


  • There are no Key Terms introduced in Investigation 3.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.


  • Imagine that you have to design an experiment investigating the effect of light on photosynthesis. Suggest a procedure that would answer this question.
  • Throughout this Investigation, you will find one way to explore the effect of light on photosynthesis. However, the way described is not the only way to perform such an investigation.
  • Play the video below. Remember to follow along with your SDR and make any notes that you think might be helpful.
  • After the video, divide into your lab groups to discuss strategy for the lab. For example, you may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow you to anticipate the laboratory experience you will soon encounter. You should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.

Note: Homework is posted below the video.


You should review the Investigation and video in preparation for the Lab.