Monocot and Dicot Lab

Transcription

1 Monocot and Dicot Lab 45 Name: Background Flowering plants belong to the phylum Tracheophyta. This phylum consists of only vascular plants, which means that they have xylem and phloem. The xylem transports water and minerals and the phloem transports dissolved nutrients, such as glucose produced in the leaves. The phylum Tracheophyta is divided into two classes: Gymnospermae and Angiospermae. Angiospermae are further divided into two sub-classes: Monocotyledonae (aka Monocots) and Dicotyledonae (aka Dicots). Monocots include palms, orchids, irises, and lilies. Dicots include oaks, mustards, cacti, blackberries, and sunflowers. Dicots are more diverse and include many more species than Monocots. Monocots are mostly herbaceous (green) plants with long, narrow leaves that have parallel veins. The flower parts of monocots occur in threes or multiples of three. Monocot seeds have a single cotyledon, or embryonic seed leaf, and endosperm (nutritive tissue) is usually present in mature seeds. In monocots, the vascular bundles of in the stem cross-section are usually scattered. The roots systems of monocots are usually fibrous, many small roots. Dicots can be herbaceous or woody stemmed. Their leaves vary in shape but are usually broader than monocot leaves. The veins of monocot leaves are netted. Flower parts usually occur in fours or fives or multiples thereof. Two cotyledons are present in dicot seeds, and endosperm is usually absent in the mature seed, having been absorbed by the two cotyledons. The vascular bundles of dicot stems are arranged in a circle or ring. The roots are a taproot system: one large root with smaller roots coming off the main root (tap root). Part 1 Flower Dissection Procedure: Step 1: Obtain a lily flower for your group. Handle the plant carefully, it is delicate. Answer the questions below. Questions (5 marks) 1. How many petals does your flower have? 2. How many stamen does your flower have? 3. Examine the leaves. a. Describe the pattern of the veins (vascular system). Is it parallel or net? b. Describe the shape of the leaves. 4. Based on your findings, is the lily plant a monocot or a dicot?

2 Step 2: Use the same lily from Part 1. Remove 2 petals and one of the stamens, so that all of the flower s reproductive parts are visible. In the space below draw the flower, neatly and in pencil! (10 marks) Label: petal, sepal, anther, filament, stamen, stigma, style, ovary

3 Step 3: Using a scalpel, carefully slice the stigma, style and ovary down the center. longitudinally. In the space below draw the internal features of the female reproductive organs, neatly and in pencil. (10 marks) Label the sigma, style, ovary, ovules

4 Part 2 Growing Monocots & Dicots (20 marks) We have already carried out the lab described below. Now you need to examine your observations made over the month of growing your plants and answer the questions on the next page. Purpose:To determine whether a germinating seed indicates if a plant is a monocot or a dicot. Materials: glass or plastic jar paper towels bean seed corn seed two other seeds Procedure: 1) Line each jar with a double layer of wet paper towels. Leave 2cm of water in the bottom of the jar. IT IS IMPORTANT THAT THE TOWELS BE KEPT WET THROUGHOUT THE ACTIVITY! 2) Position the seeds so they are wedged between the wall of the jar and the wet towels. Label the name of the seed using masking tape on the outside of the jar. 3) Predict which seeds are monocots and which seeds are dicots. Record your predictions in PEN and show them to your teacher. 4) Examine the germinating seeds daily until the roots and shoot are established. 5) Allow a month for the completed activity. Record your observations and drawings in a daily log. Be sure to label your drawings. Observations: Create a Table in your notebook as follows: Day: Date: Notes: Sketches (labelled)

5 Monocot/Dicot Lab Name: 1) Why do the seeds need to be soaked in water before planting? /1 2) Why is it important to keep the paper towel lining of the cup wet during the lab? /1 3) Which of the species you germinated was a monocot? Which one was/were a dicot? /1 4) Which of the species were the first to germinate in your experiment? /1 5) Suggest a way that being an early bloomer might be an advantage for an annual plant (a plant that only lives for one year)? /1 6) Suggest a way that being an late bloomer might be an advantage for an annual? /1 7) Did you have any seeds that did not germinate at all? Suggest a reason why, for the same species, one seed might germinate, and one not germinate, despite being kept in identical conditions. /1 8) In your opinion, what advantage do plants with woody stems have over herbaceous (non-wood) stems? /1 9) How does the arrangement of vascular bundles in a monocot stem differ from a dicot stem? /1 10) How does the arrangement of vascular bundles in a monocot root differ from a dicot root? /1 11) How do the veins in a monocot leaf differ from a dicot leaf? /1

6 Conclusion: What are the differences between monocots and dicots, as seen when their seeds germinate? Remember when stating differences, include the characteristics of both to show how they are different. /2 Attach your observations to this lab and hand it all in together. (13 marks + 7 marks)