Procedure
Part A - Scientific Observations Using Human Senses

• Use your senses to observe the citrus fruit in Figure 1.
• Answer questions 1a and 1b in Part A of your Lab Report (The link to the Lab Report is in upper right hand corner).
• Be sure to use the anatomical terms above and include a description of size, color, shape, etc.
• Quantify wherever possible.

A slice of grapefruit viewed by naked eye showing the exterior pericarp and the inner pulp. Externally the outer layer of the pericarp, the exocarp is yellow and pitted, the middle mesocarp is thick and white, the endocarp is thin. Internally the fruit is divided into many segments each with juicy sacs and a seed is visible.

Figure 1 - Grapefruit

Part B - Observations Using Laboratory Tools
The Hand lens

• The Hand Lens allows you to see more detail.
• It magnifies the object 10x.
• Use the hand lens to re-examine the fruit now shown magnified in Figure 2.
• Answer questions 2a, 2b & 3 in Part B of the Lab Report.
• As you make observations use anatomical terms discussed and be specific.
• Make sure you have observations for BOTH interior and exterior anatomy.

Image of Grapefruit Magnified by a Hand Lens. We are zoomed in 10 times on the fruit. Externally you can now clearly see oil pits in the exocarp. Internally you can see the walls of the juice sacs clearer.

Figure 2 - Grapefruit Magnified by a Hand Lens

Part B - Observations Using Laboratory Tools
The Dissecting Microscope

• The Dissecting microscope allows you to see even more detail.
• It magnifies the object 8x-32X
• Use the Dissecting Microscope to re-examine the fruit now shown magnified in Figure 3.
• Record observations in your Lab Report (Part B questions 4a, 4b & 5)
• As you make observations use anatomical terms discussed and be specific.
• Make sure you have observations for BOTH interior and exterior anatomy.

An anatomy of grapefruit slice viewed under a dissecting microscope showing the exterior part containing exocarp and mesocarp. The exocarp’s oil glands are even clearer and you can see that the mesocarp extends up into the exocarp separating the oil glands. The interior portion endocarp showing segments and juice vesicles. You can see a bubble internally as well.

Figure 3 - Grapefruit magnified with Dissecting Microscope

Part C - Deductions from Observations

• Observe other citrus fruits shown in Figure 4 and answer questions 6 - 23 in Part C of the Lab Report .

Image of other citrus fruits including Citrus paradisi (Grapefruit) which is the largest and is orange in color and juicy and divided into segments internally, Citrus sinensis (Orange) which is medium sized, orange in color and juicy and divided into segments internally, Citrus aurantifolia (Lime), which is the smallest and is green in color and juicy and divided into segments internally and Citrus limon (lemon) which is medium sized, yellow in color and juicy and divided into segments internally.

Figure 4 - Other Citrus Fruits



• Observe the apple shown in Figure 5 and answer questions 24 - 27 in Part C of the Lab Report.

Figure 5 shows red apples whole and with slices. The slice of the apple shows a thin external covering filled with a solid white inside that is not broken into segments.

Part D - Designing an Experiment

• We will start an experiment to determine where the mass of a plant comes from. We will give the plant time to grow and complete this experiment during lab 4. You will have to come back to this lab to see the original data.
• Where do you think the mass of a plant comes from?  Can you come up with a hypothesis (a testable explanation)? This is not something to look up. Where do you think the mass of a plant comes from?
As long as it is a testable explanation, it is a good hypothesis!
• Answer Questions 28 in your Lab Report.

• Watch the video below to answer question 30 and see where Jan Baptist van Helmont and other people think the mass of a plant comes from.

Watch Video

• The Slides below show images of this experiment being set up.
There are 6 slides. Navigate to the next slide using the green arrow.
Use the data on these slides to answer the questions 31 - 33 in Part D of your Lab Report.
• During Lab 4 we will weigh the soil and bean plant after it has grown to see if the mass of the plant came from the soil.

An empty cup measured using an electronic balance showing 19 grams mass.
A cup with potting soil measured using an electronic balance showing 230 grams mass
Three beans measured  using an electronic balance showing 1 gram mass
 A cup with three beans on top of potting soil.
A cup with beans covered with potting soil
A cup with watered beans in potting soil placed in a sunny spot.

After you have submitted your Lab Report Via Google please go to Blackboard, select the Lab for this week and the "Grading Rubric" . Then select "Write Submission" and type in "I have submitted my Lab Report Via Google docs"
This will allow me to enter a grade that you can see on Blackboard in your grade book for each lab.

Non-majors College Biology Lab Manual © 2021 by Marie McGovern Ph.D. is licensed under CC BY-NC 4.0