Plants and Photosynthesis. Chapters 6 and 31

Transcription

1 Plants and Photosynthesis Chapters 6 and 31

2 Unit 11, Lecture 1 Topics: Introduction to Plants The Shoot System: The Flower Covers information from: Chapter 31 (PG )

3 Terms to Describe Plants Eukaryotic Organism made up of cells that contain a nucleus and other membrane-bound organelles Plants also have specialized cellular structures not common in other eukaryotic cells: Cell wall, Chloroplast, Vacuole Multicellular Made up of more than one cell. Cells are specialized (differentiated). Cells with the same function are grouped together into tissues. Groups of tissues are grouped together into an organ.

4 Terms to Describe Plants Autotroph An organism that can make its own food using inorganic molecules Producer Base of food chain (food web) for an ecosystem, serves as a food source for consumers (Heterotrophs) Photosynthetic Uses sunlight as the energy source to produce food from carbon dioxide

5 Four Main Parts of a Flowering Plant Shoot System Shoot system made up of stem, flower and leaves Flower Leaf Root System

6 Importance of Shoots Shoot system is made up of flowers, leaves and the stem.

7 Importance of Shoots: The Flower Flowers are responsible for reproduction and seed development. Flowers contain pollen (male gamete) and/or ovules (female gamete). After pollination of the flower and fertilization of the ovule, the ovule develops into a fruit. Pollination fertilization of a flower

8 Importance of Shoots: The Flower Some flowers contain both the stamen (male) and carpel (female). These flowers can fertilize themselves. Some flowers only contain one gamete (male or female). These flowers rely on pollinators to reproduce. Examples of pollinators: bees, butterflies, bats, wind After a flower is pollinated, the ovule begins to grow larger and becomes a fruit. The fruit provides a covering for the seeds inside. The seeds may eventually germinate (sprout) and begin to grow into another plant. Fruits have seeds, vegetables don t!

9 End of Lecture 1

10 Unit 11, Lecture 2 Topics: The Shoot System: Leaves and Stem The Root System Covers information from: Chapter 31 (pgs )

11 Importance of Shoots: The Leaf Responsible for food production, main site of photosynthesis Most leaves grow at the top of a plant and are thin and flat Can be used to identify different species of plant based on the size, shape and arrangement of leaves Specialized leaves: Vines coiled leaves known as tendrils Carnivorous leaves used as a food trap Spines modified leaves for protection

12 Specialized Leaves

13 Parts of a Leaf Blade broad, flat portion of leaf Petiole structure that attaches leaf to stem Stoma pores in leaf When open, allows carbon dioxide (CO 2 ) to enter and oxygen gas (O 2 ) and H 2 O to exit Closes when too hot to prevent plant from losing too much water (would become dehydrated)

14 Types of Leaves Simple leaf one leaf per petiole Example: Maple leaf Compound leaf blade divided into leaflets Example: Clover Doubly compound leaf each leaflet divided into smaller leaflets Example: Honeylocust

15 Importance of Shoots: The Stem Stem Contains xylem and phloem, specialized tube-like tissue for transporting water, minerals, food and nutrients throughout the plant Xylem carries material from roots upwards to leaves and flower Phloem carries material from leaves down towards roots Supports leaves and flowers Site of photosynthesis in some plants

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17 Importance of Shoots: The Stem Stem Most stems grow above ground Different stem shape and growth show adaptations to the environment Strawberries stem grows along soil s surface Potato stem stores starch, grows underground Cactus stem stores water and is the site of photosynthesis Roses stem has thorns for protection

18 Specialized Stems

19 Importance of Roots Responsible for: Anchoring plant in the ground Supporting the shoot system (stem, flower, leaves) Absorbing water and nutrients from the soil Storing food Many different types of roots Most grow underground Large roots (store food) carrot, radish, turnip Numerous small roots grass Deep roots trees Some trees have toots that can grow as deep as 164 ft!

20 Types of Roots

21 End of Lecture 2

22 Unit 11, Lecture 3 Topic: Photosynthesis Covers information from: Chapter 6 (pgs )

23 Photosynthesis Photosynthesis is a series of complex chemical reactions Reactants (materials needed): Carbon Dioxide Gas (CO 2 ) Water (H 2 O) Energy (Sunlight) Final Products: Organic Compounds (Food, Sugar, Glucose, etc.) Oxygen Gas (O 2 )

24 Where does photosynthesis happen? Mainly in the leaf of a plant Leaves have tiny pores, called stoma, that can open up to absorb carbon dioxide gas Leaves have a broad, flat blade to absorb a lot of sunlight

25 Where does photosynthesis happen? Leaf cells contain numerous chloroplasts, the organelle where photosynthesis occurs Chloroplast specialized organelle Has a double membrane, its own DNA and makes energy (similar to mitochondria) But, chloroplasts also store chlorophyll, the pigment needed for photosynthesis to happen

26 How does photosynthesis happen? Photosynthesis happens in two main stages: 1. Light Reaction Needs water and sunlight, only happens during the day 1. Calvin Cycle Needs carbon dioxide and products from the light reaction, can happen at any time (day or night)

27 The Light Reaction In the light reaction, sunlight energy is transferred into cellular energy. Chlorophyll molecules (inside chloroplast organelle) absorb the sun s energy. The chlorophyll molecule absorbs so much energy, that it loses an electron. The electron then combines with another molecule, NADP + to make NADPH NADPH type of cellular energy

28 The Light Reaction Water molecules are broken apart into electrons, protons and oxygen gas The electrons attach to the chlorophyll molecules that lost their electrons The protons are used to create ATP, another type of cellular energy Oxygen gas is also created during this reaction. The oxygen gas is released as a waste product. Summary of Light Reaction: Needs chlorophyll (in plant), sunlight and water Produces NADPH (cellular energy), ATP (cellular energy) and O 2 (waste product)

29 The Calvin Cycle NADPH and ATP are great forms of energy for the plant, however these energy molecules break down quickly and cannot be stored for later use. In the Calvin Cycle, these energy molecules (NADPH and ATP) are used to transform Carbon Dioxide gas into food! This process is known as Carbon Fixation. Any type of organic compound (food) can be created during the Calvin Cycle Types of organic compounds: Carbohydrates Glucose, Fructose, Maltose, Starch, Cellulose Amino Acids can then be used to make proteins Lipids Saturated fats, Unsaturated fats, Wax, Phospholipids (to create new cell membranes)

30 The Calvin Cycle Carbon Dioxide (CO 2 ) gas enters leaf through the stoma and diffuses into the chloroplast CO 2 combines with RuBP (a 5-carbon molecule) Once CO 2 combines with RuBP, it creates a 6-carbon molecule. This then splits in half to form two 3-carbon molecules known as PGAL. This step requires 2 ATP and 2 NADPH molecules to occur Some PGAL molecules are stored and can be built up to form organic compounds Most PGAL is transformed back into RuBP to start the Calvin Cycle again. (This step also requires ATP to occur)

31 The Calvin Cycle Summary of Calvin Cycle: Needs RuBP, NADPH, ATP and Carbon Dioxide to happen Produces PGAL which is used to make food (organic compounds) The food products are then carried by the phloem through the plant. The excess can be stored in leaves, fruits, seeds, roots, as vegetables, etc. Sweet Potato Radish Papaya Tree

32 Summary of Photosynthesis Combines two steps (Light reaction and Calvin Cycle Carbon Dioxide + Water + Sunlight Glucose + Oxygen Gas Chemical Formula (Yes, you have to know this!!!) 6CO H 2 O + Light Energy C 6 H 12 O O 2

33 Rate of Photosynthesis Affected by the environmental factors such as: Light, Temperature, Amount of CO 2, Amount of H 2 O Amount of light Most important factor More light = More photosynthesis Rate of photosynthesis will increase, up until a certain point, then levels off (plateau)

34 Rate of Photosynthesis Temperature Increasing temperature = More photosynthesis Rate of photosynthesis will increase up until a certain point, then decreases High temperatures cause stoma to close Stoma pores in leaves that absorb CO 2 If stoma are closed, plant not getting supply of CO 2 & the Calvin Cycle won t be able to occur

35 Rate of Photosynthesis Amount of Carbon Dioxide More carbon dioxide = More photosynthesis Rate of photosynthesis will increase, up until a certain point, then levels off (plateau) Amount of Water More water = More photosynthesis Rate of photosynthesis will increase, up until a certain point, then levels off (plateau)

36 End of Lecture 3