9. Place five pea seeds at equally spaced intervals in the dish (figure 1) 10. Place both treatments under the grow lights in the appropriate location labeled with your lab section. 11. In one week we will be collecting the pea seeds and drying them (to remove water weight) and we will then weigh them again. Develop a hypothesis to explain what you expect to happen to the weight of the seeds in each treatment. You should carefully consider the energy metabolism of seeds and how seeds will store and use energy under each treatment. Figure 6: evenly spaced peas in a petri dish.Table 2: Initial mass of peas before treatment Treatment Initial Mass at Room Humidity Peas (g) Initial Mass at Room Humidity / 5 Pea (g) Light and Water Light Only
35 FAST plants experiment: Maturing Seeds Your seed pods should be fully developed and the seeds inside germinating. 1. Gently water the plants until the soil is moistened. 2. Look at those seed pods!
36 Reflection Questions – Answer these to help prepare for next week’s quiz! 1. Some of the ill effects of lactose intolerance are due to the activity of bacteria digesting sugar like lactose and glucose in the large intestines. We discovered in our lactase lab that if lactose sugar is not exposed to the enzyme lactase it cannot be broken down. How does the presence of lactase in the small intestine where nutrients are absorbed across intestinal cells keep bacteria from being over-supplied with sugar in the large intestine? 2. The dialysis bag is a good model for the outer boundary of a living cell. Predict any difficulties in obtaining nutrients for a person with a genetic defect causing a deficiency in their invertase activity. 3. If you chew a saltine cracker or a piece of bread for a long time (try it!) you may notice that the starchy food begins to taste sweet. What is the biological explanation for this phenomenon? 4. Why are glucose and water able to cross the dialysis (or cell) membrane when starch cannot? 5. Why is there a difference in osmosis across a dialysis membrane when invertase is incubated at normal human body temperature or when it is placed on ice? 6. What do you predict would happen in an osmometer if any enzyme like pepsin or lactase were added to a sucrose solution? 7. When you examine your graph of osmosis, how does the rate of osmosis (amount of movement over time) change? Does it speed up, slow down, or stay the same? Why do you think this is? 8. If you were able to let your osomometer run for the rest of the day, what do you think would happen to the fluid movement? Why?