IB Biology Review

1. IB Biology Review Chapter 35: Plant Structure

2. What are the two types of plants IB focuses on? Angiosperms Monocots / Monocotyledonous Eudicots / Dicots / Dicotyledonous What do the names mean? Monocot: One cotyledon Dicot: Two cotyledons What is a cotyledon? Seed leaf

3. What are the main structures in a plant? Leaves Stem Roots Flowers

4. How does leaf structure differ in monocots and eudicots? Monocots Parallel leaf veins Eudicots Netlike leaf veins

5. How does the arrangement of vascular tissue differ in monocots and eudicots? Monocots Scattered throughoutstem Eudicots In a ring on the edge of the stem

6. How does the root structure differ in monocots and eudicots? Monocots Fibrous root No main root Eudicots Taproot Primary root

7. How does the number of flower parts differ in monocots and eudicots? Monocots Petals etc. in multiples of 3 Eudicots Petals etc. in multiples of 4 or 5

8. Function of Leaf Tissues Palisade Mesophyll main photosynthetic cells (have many chloroplasts) in leaf located near top of leaf (sun) to maximize rate of photosynthesis Spongy Mesophyll near bottom of leaf where CO2 enters stomata and oxygen and water leaves air spaces between cells allow gas movement Xylem centrally located next to palisade mesophyll provides easy water and nutrient supply to palisade cells for photosynthesis

9. Function of Leaf Tissues cont. Phloem centrally located next to palisade mesophyll takes away sugars produced by photosynthesis Guard cells and stomata located on the bottom of the leaf because that is where gas and water vapor exchange occur this way, no interference with photosynthesis Upper epidermis Top layer of cells where sun hits the leaf, covered with cuticle Cuticle waxy coating to prevent water loss

10. Leaf and Leaf Tissue Structure Cuticle Upper / lower epidermis Palisade mesophyll Xylem Phloem Spongy mesophyll Guard Cell Stoma

11. Stem Structure in Eudicots Consists of Epidermis Vascular Bundle Xylem Phloem Cortex Endodermis Pith BE ABLE TO DRAW THIS

12. Function of Roots What do roots do for the plant? Absorb nutrients Absorb water Keep the plant in the ground For some, roots store excess energy What are root hairs? Small root-like projections off the root Increase surface area of root

13. What are two modifications of leaves? Spines (as on a cactus) protect the plant from herbivory Tendrils (as on pea plant) help the plant cling to objects for support and growth

14. What are two modifications of stems? Stolons (as on raspberry plant) horizontal stems that grow along the ground surface and allow the plant to extend itself into adjacent areas fast a form of asexual reproduction Bulbs (like onion) Vertical underground shoots consisting of enlarged leaves that store food

15. What are two modifications of roots? Storage roots (like sweet potato) purpose is storage of starch and water Pneumatophores/ air roots (as in mangroves and bald cypress trees) these roots extend above the surface of the water in waterlogged soils to allow oxygen to get to the roots

16. Two Types of Plant Growth Apical Vertical growth / height Lateral �Sideways� growth / width Which group of plants (monocots/eudicots) usually has both apical and lateral growth? Eudicots

17. Apical and Lateral Growth Where does growth occur? Apical meristems Extend the length of root or stem Cell division occurs in meristematic region (zone of elongation) at the end of root or stem Lateral Meristems Increase girth of stem Cell division occurs in vascular cambium around stem

18. Function of Auxin plant hormone that stimulates cell elongation one of the processes that auxin controls is phototropism directional growth toward the source of light shoot tips respond to light intensity by producing more auxin on the side with less light, making that side grow longer, thus bending the shoot tip toward the light

19. Function of Auxin

20. 1. Outline three differences between the structures of dicotyledonous (eudicot) and monocotyledonous plants. (6 marks) Monocots One cotyledon Parallel leaf veins Scattered vascular tissues Fibrous root system Flower parts in multiples of 3

21. 2. The leaves of plants are adapted to absorb light and use it in photosynthesis. Draw a labelled diagram to show the arrangement of tissues in a leaf. (6 marks) Award [1] for each of the following structures, shown in the correct relative position and labelled. Individual cells are not needed but do not penalize if they are shown. upper epidermis; palisade layer / mesophyll; spongy layer / mesophyll; lower epidermis; xylem (in a major or minor vein); phloem (in a major or minor vein); guard cells; (do not accept stoma/stomata only)

22. 3. Draw and label the tissues within a leaf and explain the relationship between the distribution of those tissues and their function. (12 marks) palisade mesophyll: Main photosynthetic cells in leaf, located near top of leaf to maximize rate of photosynthesis spongy mesophyll: Near bottom of leaf where Co2 enters stomata and oxygen and water leaves � air spaces between cells allow gas movement. xylem: Centrally located next to palisade mesophyll to provide easy water and nutrient supply to palisade cells for photosynthesis phloem: Centrally located next to palisade mesophyll to take away sugars produced by photosynthesis guard cells: Located on the bottom of the leaf because that is where gases enter. This way, no interference with photosynthesis upper epidermis: On top of leaf � they have a waxy coating to prevent water loss (sun is hitting top)

23. 4. Identify and describe modifications of roots, stems, and leaves for different functions ( 10 marks) Storage roots (like sweet potato): purpose is storage of starch and water Pneumatophores / air roots (as in mangroves and bald cypress trees): these roots extend above the surface of the water in waterlogged soils to allow oxygen to get to the roots Stolons: horizontal stems that grow along the ground surface and allow the plant to extend itself into adjacent areas fast. Is a form of asexual reproduction Bulbs (like onion): vertical underground shoots consisting of enlarged leaves that store food Spines (as on a cactus): protect the plant from herbivory Tendrils (as on pea plant): help the plant cling to objects for support and growth

24. 5. Compare growth due to apical and lateral meristems in dicotyledonous plants. (3 marks) Apical meristems Extend the length of root or stem Cell division occurs in meristematic region (zone of elongation) at the end of root or stem Lateral Meristems Increase girth of stem Cell division occurs in vascular cambium around stem

25. 6. Explain the role of auxin in phototropism. (6 marks) shoots of plants grow towards light / positively phototropic; roots grow away from light / regularly phototropic; shoot tips produce auxin; acts as a growth promoter allows cell expansion; is distributed in the tip from the lighter to the darker side; plant bends towards the light;