16B Flower Dissection

Transcription

1 16B How does the design of flower help in its pollination? Do you know where the saying the birds and the bees came from? It all started with flowers. Plants require pollinators like birds and bees to carry their pollen to fertilize other flowers. Without the pollen, flowers would not be able to create seeds for reproducing. An adaptation is an advantage in the physical design or behavior of an organism. An adaptation helps the organism to survive or reproduce. In this investigation, you will examine flowers to determine how they may have adaptations that increase their chances of pollination. Materials Large flower Dissecting scissors Hand lens Metric ruler Microscope Slide Cover slip Water Plastic dropper Newspaper A Setting up A flower s only purpose is reproduction for the plant. In addition to male and female parts, flowers have petals and sepals. Do the sepal and petals help with pollination? Let s find out. Open a sheet of newspaper. This will be your work area. Lay the flower on the newspaper. Make a detailed sketch of what you see and record any observations in the spaces provided. Pay close attention to the color, smell, shape, and feel of the flower. 11 B Stop and think a. A quantitative observation is an observation that deals with a number or an amount. What quantitative observations can you make about the flower? 1

2 b. A qualitative observation is an observation that describes shape, appearance, etc. What qualitative observations can you make about the flower? c. Make a hypothesis stating ways the flower may be designed to help in pollination. Use what you know about flowers and the birds or bees that pollinate them. C Removing the Sepal and Petals 1. Record the number and color of the sepals in Table Gently pull the sepals away from the flower. If necessary, use dissecting scissors to cut away the sepals. Always cut away from yourself. Cut carefully so the structures underneath are not damaged. 3. Record the number and color of the petals in Table Gently pull back each of the petals revealing the male and female parts inside. 5. In the box provided, draw what you see. Label an anther, a filament, the stigma, the style, and the ovary. Also label the entire pistil and stamen. D Examining the male parts of the flower 1. Use the scissors to cut off all of the stamens. Record the number and color of the stamens in Table At random, select three stamens. Measure the length, in mm, of each of the three stamens. Record your results in Table 2 and calculate the average. 2

3 3. Collect a slide. Tap the stamen over the slide so that the pollen falls onto the slide. Add a drop of water to the slide and place a cover slip over the water and pollen. 4. Place the pollen slide on the microscope stage and observe the pollen grain under low power, medium power, and high power. Make a detailed sketch of one pollen grain at the highest power. Sketch the drawing in the space provided Estimate the number of pollen on one anther. Record the estimated number and color of the pollen grain in Table 1. E Examining the female parts of the flower 1. Record the number and color of the pistil in Table Use the scissors to carefully cut away the pistil. Attempt to cut the pistil as close as you can to its base. 3. Measure the length, in mm, of the pistil and record your results in Data Table Examine the overall appearance of the pistil and note any unique qualities. 5. Firmly hold the pistil flat on the newspaper. Use the edge of your scissors to cut across the ovary exposing the inside compartments. 3

4 6. Use the hand lens to examine the ovary. Estimate and record the number and color of the ovules in Table 1. Table 1: Number and color of the flower structure Flower Structure Number Color Sepals Petals Stamen Pollen Grains Estimate: Pistil Ovules Estimate: 7 Table 2: Length of the stamen and pistil measured in mm Flower #1 #2 #3 Average Stamen Pistil F Thinking about what you observed a. What aspects about the overall flower shape, color, smell, size, or position, help attract pollinators? b. What is the benefit to the plant if the flower attracts a pollinator? c. There are several stamens and only one pistil. What might be the reasoning for this design? 4

5 d. Compare the length of your pistil to the average length of the stamen. Why would one be longer than the other? e. Explain the process of a bee pollinating a flower. G Exploring on your own After the female parts of the flower are pollinated, it may develop into fruit. Obtain a piece of fruit. Try to match parts of the fruit to parts of the flower from which they developed. Or Different flowers are designed for different pollinators. For example, some flowers are pollinated by bees. Others are pollinated by the wind. Would a flower have any major differences because of the type of pollinator? Design an experiment to find the answer. Check in with your teacher before carrying out your investigation. 5