Biology

Lab 5: Seed-bearing Plants

Materials needed

Sharp knife

Cutting board

Large pine cone with open “scales”

Fascicle (bundle) of pine needles

2 household cups (may be disposable)

Measuring cup

Red food coloring

Blue food coloring

Salt

Celery stalk

Pea pod: sugar snap pea or snow pea

Dry lima beans (3)

Activity: anatomy of pine

1. Obtain a pine cone and a fascicle (bundle) of pine needles. Refer to Figure 5.1 as you perform this activity.

2. Examine the fascicle of pine needles (Figure 5.1). A pine needle is actually a leaf. It has green pigmentation for photosynthesis. It is skinny, leathery, and coated with a sticky resin to help retain water. Pine needles are bound together in a bundle (fascicle). Different species have different numbers of needles per fascicle. For example, white pines (Pinus strobus) have five needles per fascicle, while red pines (Pinus resinosa) have two needles per fascicle.

3. Examine the large pine cone (Figure 5.1). It should be large enough to fit into your palm, andits woody “scales” should be open. Pine trees produce two kinds of cones: pollen cones and seed cones (or ovulate cones). Pollen cones are small – they often are not much bigger than the last digit of your pinky finger. These cones produce pollen grains, which contain sperm. You should have a larger cone, the seed cone. Each woody “scale” of the seed cone typically produces two eggs at its base. Before the eggs are fertilized, the seed cone is closed up. Pollen grains blow into the cracks between the closed scales, and fertilize the eggs. The fertilized egg then develops into a seed, and the scale opens. The scales are called sporophylls (“spore” + “leaf”).

4. Break off a few scales near the top of the cone. Examine the base. You should see two indentations where the seeds used to be. Examine or break off a few scales near the bottom of the cone. There may be seeds present (Figure 5.1). The pine seed has a “wing.” This enables the seed to disperse away from the parent plant via the wind. This is why the scales open up once the seed develops.

5. A seed cone usually does not release all of its seeds at once. Thus, part of the cone, usually the top, is often more “open” than other parts. Because pine cones rely on the wind to disperse seeds, it is important that the “wing” of the seed stays dry. Pine cones protect developing seeds from becoming waterlogged through a passive reaction.

a. Place your open seed cone into a cup of tap water.

b. Record: Time into water _________

Describe your observations and any changes in the cone appearance

c. Let the cone sit in the water for at least 30 minutes.

d. Record: Time out of water _______

Describe your observations and any changes in the cone appearance

Fig 5.1

Lab Report

This is an experimental variation on the celery food dye activity of Lab 5.

Activity

1. Obtain four cups (two of which could have been used in Lab 5). As in Lab 5, fill each cup with 400 ml of tap water. Use red dye to darkly stain two cups, and use blue dye to darkly stain the other two cups. Be sure that each red cup gets the same amount of dye and that each blue cup gets the same amount of dye. Record the drops in each. Add a spoonful of salt into each cup.

2. Label one red dye cup and one blue dye cup with an S (high salt). Add 4 spoonfuls of salt to each of these cups. Stir the solutions thoroughly.

3. Obtain two similar stalks of celery, each with some leaves at the top. Cut a 1-cm piece (about one-half inch) off the bottom of each stalk. Keep the relative lengths of the two stalks as similar as possible.15

4. Carefully, split the stalks up the middle about half-way. The stalks should each now have two “legs.” Be sure that the legs of each stock are similar sized (i.e., the left leg and right leg are the nearly the same length and width).

5. Place the red S cup and the blue S cup together. Gently place one “leg” of one stalk into the red S cup, and the other “leg” of the stock into the blue S cup. The celery should now be “straddling” the two S cups (Figure 5.2.B). Place the red non-S cup and blue non-S cup together and situate the legs of the other celery stalk into each cup (i.e., the celery “straddles” these two non-S cups).

6. Record the time at which you place each celery into the pairs of cups as “Start time.”

Start time Stop time
a. S cups (high salt)
b.Non-S cups (low salt)

7. Let the celery sit in the cups for 6 hours, or until you can see color in the leaves of one of the stalks. In Step 6 above, record the time when you remove the stalks as “Stop time.”

8. Examine the top of the celery stalks. Are there differences between the celery in the high salt (S) and low salt (non-S) water conditions? Record your observations in Question 1 of Lab Report 6.

9. Remove the celery from the cups (be sure to keep it clear which came from the high salt solution (S) and which came from the low salt (non-S) condition). Lay each stalk out flat. Starting at the top, move down the stalk, making cross-sectional cuts. Stop when you first see evidence of dye. Measure how far up each stalk the red and blue dyes climbed. In Table 6.1 in Lab Report 6, record the distance (cm) traveled by the red dye in high salt conditions (S), the blue dye in high salt conditions (S), the red dye in low salt conditions (non-S) and the blue dye in low salt conditions (non-S).

10. Tear apart the celery stalk. Notice the feel of the vascular tissue, and how the food coloring lies within it.

Lab 6A: Water transport and salinity

1. Examine the top of the celery stalks. Are there differences between the celery in the high salt and low salt water conditions? Describe your observations.

2. Record the distance (cm) traveled by the red dye in high salt conditions (S), the blue dye in high salt conditions (S), the red dye in low salt conditions (non-S) and the blue dye in low salt conditions (non-S).

Table 6.1

Distance (cm)

Red dye (S)

Blue dye (S)

Red dye (non-S)

Blue dye (non-S)

3. From Question 2 above, did the dyes travel at the same rate? What can you conclude about the effect of salinity on water transport in celery from this experiment? Propose a biological or physical explanation for your conclusion.

Activity: seeds

1. Obtain a sugar snap pea pod, or a snow pea pod. This is the fruit that develops from the pea flower (Figure 5.4). In this case, the fruit is not as sweet or as juicy as an apple. Cut along the curve of the pod. This exposes the seeds (peas) on the inside. You should be able to crack the peas in half. This reveals that the seed is composed of two cotyledons (seed “leaves”). The cotyledon becomes the main food source as the seed starts sprouting.

2. Angiosperm plants are divided into dicots (Class Dicotyledonae) and monocots (ClassMonocotyledonae). There are 180,000 species of dicots, including many flowers, shrubs,and trees. Dicots are distinguished by seeds with two cotyledons (e.g., bean, peanut, pea),leaves with veins having a branching pattern (e.g., maple, oak), and flower parts in multiples of four or five (e.g., four petals of poppies, five petals of wild roses). There are 80,000 species of monocots, including grasses and important crops (e.g., wheat, corn, rice), palms, and orchids. Monocot seeds have one cotyledon (e.g., corn kernel), leaves with parallel veins (e.g., blade of grass), and flower parts in multiples of three (e.g., six petals on lilies).

3. Obtain a few dry lima beans. Soak them in a cup of tap water for at least 8 hours.

4. Gently dry the beans on a paper towel. With your finger, you should be able to gently peel off the outer seed coat (if you cannot, soak the bean for 1-2 more hours).

5. Using a knife, carefully cut along the curvature of the bean. You should then be able to break the bean in half. Each half is a cotyledon, which has become swollen with nutrients from the endosperm.

6. Examine the embryo (see Figure 5.3). At minimum, you should be able to recognize the leaflike tip of the epicotyl (Figure 5.4). Look for the hypocotyl and the radicle.

5.3

5.4 5.4

5.4

1. Anatomy of a pine.

a. Place your open seed cone into a cup of tap water.

b. Record: Time into water _________

Describe your observations and any changes in the cone appearance

c. Let the cone sit in the water for at least 30 minutes.

d. Record: Time out of water _______

Describe your observations and any changes in the cone appearance

2. Vascular transport.

a) Examine the top of the celery stalk. Describe your observations:

b) Make a cross-section cut where the celery stalk has not been split. Describe your observations:

Lab 6B: Seed germination and environmental conditions

In this experiment, you will investigate germination of radish seeds in environments with

different salt contents. You will prepare six germinating environments and monitor them

over four days. Each germinating environment will be a plastic-encased, water-soaked

paper towel.

Activity

1. To prepare solutions of different salinity, collect 6 clean cups and label them: “1/2”,

“1/4”, “1/8”, “1/16”, “1/32”, and “0”.

2. Use a measuring spoon to add salt to 50 ml of water in a measuring cup (about 1/4

cup). Add 1.5 tablespoons of table salt (sodium chloride). Stir the water while adding

the salt. The solubility of sodium chloride is ~36 grams per 100 mL of fresh water at

25 C. After vigorous stirring the solution you should still be able to see some

remaining some salt crystals at the bottom of your solution. This indicates that you

have reached the saturation point of salt in your water.

3. Pour off 40 ml of salt water into the cup labeled ‘1/2.” Do not pour the un-dissolved

salt. The “1/2” cup will then contain your saturated salt water solution.

4. Clean your measuring cup, and fill each of the remaining cups with 40 ml of plain

water.

5. Add 40 ml of plain water to your salt solution in the “1/2” cup. You will then have 80

ml of a 50% saturated saline solution in the “1/2” cup.

6. Using your measuring cup as an intermediate, transfer 40 ml the 50% saturated

solution (“1/2” cup) to the cup labeled “1/4”. The “1/4” cup will then hold 80 ml of a

25% saturated saline solution.

7. Using your clean measuring cup as an intermediate, transfer 40 ml the 25% saturated

solution (“1/4” cup) to the cup labeled “1/8”. The “1/8” cup will then hold 80 ml of a

12.5% saturated saline solution.

8. Using your clean measuring cup as an intermediate, transfer 40 ml the 12.5% saturated solution (“1/8” cup) to the cup labeled “1/16”. The “1/16” cup will then hold 80 ml of a 6.3% saturated saline solution.

9. Using your clean measuring cup as an intermediate, transfer 40 ml the 6.3% saturated solution (“1/16” cup) to the cup labeled “1/32”. The “1/32” cup will then hold 80 ml of a 3.1% saturated saline solution. 17

10. You have now prepared a pure water solution in cup “0” and a 3.1%, 6.3%, 12.5%,

25%, and a 50% saturated saline solution in cups “1/32”,”1/16”, “1/8”,”1/4”, and

“1/2” respectively.

11. Alternative experiment. You have six solutions ranging in concentration from 0% to

a 50% saturated saline solution. You can run this experiment using each solution as

the basis for a germinating environment and following the instructions as they stand.

However, if you would like to discard one or two of the salt water solutions and use

two solutions of your own design in their place, this is OK. Examples include using

water with additives such as sugar, alcohol, soda, or bleach, or even running two at

the same salt concentration to get a sense of the uncertainty. You can also use the

above protocol to test the effects of even smaller salt concentrations. If you choose to

run some alternatives, you still need to run pure water and at least three of the saline

solutions, thus all of the rest of the salt concentration experiment still applies. If you

do choose to run some alternatives, simply follow the directions below with the

relevant change in mind. In the lab report, you will need to describe your alternative

experiment(s) and their outcome(s) separately. Have fun!

12. Prepare for seed germination. Take three paper towels and cut them in half. Fold

each half towel in half. These towels will be the seeds’ germinating environment.

 

Figure 6.3. Left. Radish seeds layed out on a water soaked paper towel. Right. A radish

sprout. [Image taken from the Internet, http://www.michigan.gov/kids/0,1607,7-247-

49067-65181–,00.html]

13. Place a folded towel in each of the cups containing your salt solutions and possible

alternatives. Make sure that each towel gets soaked with the solution and that you do

not lose track of which one is which condition. Label one corner of each towel with

the corresponding solution (e.g., “1/2”, “1/4”, etc.).

14. Count out six piles of 15 or more radish seeds each. Make sure that each pile has the same number of seeds. If there are visible quality differences between seeds make

sure that each pile has similar quality as well (e.g., discard cracked, broken, or

discolored seeds).18

15. Remove the soaked towels from the cups and lay the seeds from each pile out in each one of the towels (Figure 6.3). Be careful not to mix up which towel came from

which cup. Record the initial date (Day 0) in which you first put the seeds in the

towels in Table 6.2 in Lab Report 6. Spread the seeds over only one half of the towel

so that you can fold the other half over the seeds. You may even want to add another

fold.

16. Fold the towel up around the seeds in order to keep them wet, but you will also want

to be able to unfold the towel to observe the germination process over the next four

days. Wrap each wet towel with its seeds in saran wrap or in a sealed sandwich bag.

This will insure that the water in the towel does not evaporate away. Make sure that

each towel and seed set is labeled to match the corresponding solution(e.g., “1/2”,

“1/4”, etc.), perhaps by marking the plastic bag or wrap, or by placing a labeled piece

of paper in the bag/wrap.

17. Find a safe location where your seed sets can stay for the next four days. Make surethat each set is in identical conditions. Monitor seed appearance and growth every dayfor the next four days. Unfold the wet towels carefully to avoid ripping the wet towel

or fragile sprouts. Be sure to record the number of sprouts, changes over time, and

differences that you notice between seed sets in Table 6.2 in Lab Report 6.

4. Observe the radish seed and sprout. Are radishes monocots or dicots? How can you tell?

5. Describe the results of your experiment in Table 6.2. How many sprouted seeds were present in each group per day? Include any other relevant observations, such as appearance, color, etc. Include any alternative treatments or conditions.

Table 6.2. Seed germination.      
Initial date (Day 0): ________________  
  Record # sprouts, appearance, etc. per day.  
Saline solution Day 1: Day 2: Day 3: Day 4:
0% (“0” cup)        
3.1% (“1/32” cup)        
6.3% (“1/16 cup)        
12.5% (“1/8” cup)        
25% (“1/4” cup)        
50% (“1/2” cup)        
Alternative:        
Alternative:        

6. From your results in Table 6.2, draw a conclusion about the effect of salinity on sprouting success. Include conclusions drawn from alternative treatments or conditions.

Lab Report 8

   Figure 8.1. Human skeleton. The axial skeleton is shown in pink; the appendicular skeleton is

shown in tan. [From p. 180, S.S. Mader. 2004. Human biology laboratory manual, 8th

edition. McGraw Hill; New York.]

1. Using Figure 8.1, find each of the listed bones on your body. Then, using Figures 8.2 and 8.3, write in a muscle that attaches to the bone and an artery that runs alongside the bone.

Bone Muscle Artery

Cranium

Clavicle

Sternum

Humerus

Radius or Ulna

Coxal bone

Metacarpals

Femur

Tibia

Fibula

Metatarsals

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