Lab Practicum Review

1. Lab Practicum Review What does iodine test for? What are adventitious roots? Why does fresh potato cause bubbling when in peroxide? Can you identify a X.S. of a leaf, stem or root under the microscope? What are simple or compound leaves? Can you identify leaves as such? What are the types of germination? Stem structure, both external and internal. What are the differences between a monocot verses a dicot leaf? Leaf anatomy – epidermis, mesophyll, stomata, etc. What cells/tissue in plants make up what is termed “wood”?

2. Photosynthesis …..the equation Metabolism …….. the equation What is a cambium and what does it do in a plant stem? The plant cell verses animal cell…differences Plant flowers external features like sepals, petals, pistil and anthers Functions of plant ovary or anthers Anabolic verses catabolic metabolism (photosynthesis verses respiration) DNA – transcription, translation Mitosis verses meiosis

3. Seed dispersal mechanisms Dehiscent vs nondehiscent fruit Genetics/monohybrid and dihybrid crosses …..Mendel Adaptation to the environment ….anatomical changes: sunken stomates, reduced leaf size, hairs, thickened cuticle and external morphology such as lost leaves, thickened water storage stems, etc Nucleotide bases of DNA and RNA (G,C,T,A and G,C,U,A)

11. Modified Stems - Several examples of modified stems are setup around the lab. Examine each and find the features common to stems and how they have been modified from “normal” stems.

17. Guard cells of stomates in monocot grasses (upper figure) and broadleaf dicots (lower figure)

20. Leaf Modification - Plants have adapted their leaves to survive environmental extremes, as protective structures, to aid in support and even to catch and provide nutrition (insectivorous plants).

24. Below is a cross section of an ovary.

26. Plants undergo double fertilization

27. Insect pollination is responsible for producing 80% of the fruit and vegetables we consume. Wind, water and animals also help to transfer pollen.

29. Dicot seed on the left; monocot seed on right

31. Seed dispersal often requires “new ground” which can could be as simple as a field that has been plowed or a newly formed volcanic island In all these scenarios plants will eventually appear and grow. Seed dispersal is what allows for this to happen and occurs through a variety of mechanisms that have evolved over thousands of years.

32. Seed dispersal starts first with the fruit and whether it stays on the mother plant and releases the seed (dehiscent fruit) or where the seed stay within the fruit (nondehiscent fruit) which then falls or is released from the plant. Examples of dehiscent fruit are follicles, pods and capsules.

33. Wind Do you remember as a child taking dandelions and blowing their “fuzz” around? Of course the “fuzz” was seed that had feathery plumes or parachutes. The seed was so light that your breath could carry them quite some distance across a lawn. Your actions were mimicking what would happen naturally with a strong wind in the dispersal of these seed.

34. Water Most of the earth’s surface is covered with water. Water tends to move either through gravity or wind forces. Consequently, water provides an excellent method for dispersal for some plants. Plants such as Mangrove and Coconut have seed with entrapped air that makes them buoyant. These seed can drift literally thousands of miles before washing up on a shore where they can take root and grow.

35. Additionally, there is dispersal by animals after they eat the fruit, seeds that hitchhike by attaching to clothing or fur

36. Photosynthesis At the heart of this collection system is chlorophyll, a chemical substance capable of capturing photons of light and generating a high energy electron that can be used for the synthesis of food.

37. 3-D Illustrations of the chloroplast

38. There are basically two major steps in photosynthesis required to produce the carbohydrate (sugar). The first requires light energy (light dependant reaction). This energy is ultimately captured in the form of high energy compounds that we have already studied in respiration (ATP, NADH, etc). Note that the light reaction DOES NOT in itself produce any carbohydrate. The high energy compounds are shunted to the stroma of the chloroplast where the second reaction (the light independent or dark reaction) occurs to produce the carbohydrate. Like the krebs or citric acid cycle of respiration, the dark reaction is also cyclic and is known as the Calvin-Benson cycle.

40. Glycolysis

41. The diagrams below show the chemistry of this conversion. Note that in alcoholic fermentation CO2 is produced, but not in lactic acid fermentation.

42. Krebs Cycle, TCA Cycle or Citric Acid Cycle

43. Terminal Oxidation

44. DesertAdaptations - With desert conditions, conservation of water is extremely important to survival. Rainfall averages less than 10 inches per year. Consequently, plants have evolved ways to conserve or store water. Among these adaptations are:

45. Water storage tissues in stems or leaves • Leaves absent, reduced in size or short lived only when there is rain • Deep root systems to reach water or very wide root systems that efficiently capture water after a rainfall • Plants may produce a heavy thick cuticle of wax on leaves and stems to reduce water loss • Anatomically those plants that retain their leaves may show anatomical changes such as reduced number of stomates, sunken stomates or “hairy” stomates (protective trichomes that reduce water evaporation) • Leaves may develop numerous trichomes (“hairs”) that shade the leaf and reduce water loss • Photosynthesis desert and arid land plants may use C4 photosynthesis rather than C3 photosynthesis. Consequently C4 plant will show a different anatomy (Krans anatomy) in the leaves where the mesophyll is arranged around the bundle sheath cells of the veins. Additionally, the bundles sheaths will contain chloroplast in the C4 leaf whereas chloroplast are absent in the C3 leaf.

49. Temperate Grasslands Adaptation - Grasslands, also called prairies, have hot summers and cold winters. Rain is sparse and droughts common. Average rainfall is 10 - 30 inches a year. The soil of grasslands is very rich in organic matter from the annual grasses that die off and enrich the soil. Farming has claimed the majority of original grasslands. Only small patches or pockets of original grassland remain. Adaptations include:

50. Roots survive fire and resprout • Prairie trees have thick bark for fire protection • Root systems are so extensive that grazing animals cannot pull the plants from the ground • Shrubs resprout readily after a fire • Narrow leaves of grasses have less water loss compared to broad leaf plants • Extensive and deep root system to obtain water • Flexible stems that can bend in the winds typical of prairies • Most grasses use the wind for pollenation • Some grasses also utilize C4 photosynthesis