Chapter 29 Chapter review

How plants are classified, the major categories of plants, examples of plants that fit into the various categories, and the major characteristics of different types of plants

As alluded to above, plants can be broadly divided into nonvascular and vascular plants based on the presence or absence of vascular tissue, which is covered in more detail in Chapter 35. Vascular tissue consists of cells joined into tubes that transport water and nutrients throughout the plant body. Vascular tissue also gives the plant structural support. Nonvascular plants represent a more ancient lineage of plants; in other words, vascular tissue is a modern evolutionary innovation.

Evolutionary relationship between green algae and plants; significant similarities and differences between plants and their closest living relatives

Evolution of Land Plants Green algae called charophytes are thought to be the closest living relatives of land plants. They are similar to land plants biochemically, morphologically, and genetically. Although aquatic, charophytes inhabit shallow waters and dry out occasionally.

What alternation of generations is, the names of the different forms of the plant, and what each produces

One trait all plants have in common is a life cycle with alternation of generations. Alternation of generations is a characteristic of all plants, as well as some protists and fungi, but its adaptive significance is unknown - one of great, unsolved problems of contemporary biology! Background Information: A Brief Lesson in Genetics In order to understand the concept of alternation of generations, you need to know the difference between a haploid organism and a diploid organism. * DIPLOID (2n) means there are two sets of chromosomes present, one from each parent * HAPLOID (n) means there is only one set of chromosomes present. * For example, human eggs and sperm are haploid; when the egg is fertilized by a sperm, the chromosomes from the egg combine with the chromosomes from the sperm, creating a diploid zygote (a fertilized egg). Humans remain diploid for the rest of their lives. In alternation of generations, organisms alternate between multicellular haploid and diploid forms. Although all sexual life cycles alternate between haploid and diploid, they are not multicellular. For example, in humans, our haploid phase (egg and sperm) is unicellular. The way I like to explain it is that if humans had alternation of generations, our sperm and eggs would divide, developing into multicellular structures. Thus, we would occasionally bump into sperms and eggs wandering the halls for a period of time before joining together to form a human! In alternation of generations: Sporophyte (2n) produces spores (n) Spores divide and develop into a haploid gametophyte Gametophyte produces gametes (n) Two gametes unite during fertilization to form diploid zygote (2n) Zygote develops into sporophyte In many nonvascular plants ('ancient' plants), the life cycle is dominated by the gametophyte. Mosses, for example, are almost always haploid. In vascular plants ('modern' plants), the gametophyte phase is reduced; the gametophyte is often microscopic, and develops partly or entirely while attached to the sporophyte. Thus, for most plants, what you are looking at is the sporophyte. Other characteristics of nonvascular and vascular plants are covered next.

What photosynthesis is, where it occurs in the cell, and the type of nutritional mode this falls under

Photosynthesis is the process by which light energy is converted to chemical energy and stored in sugars or other organic compounds. The chemical equation for photosynthesis is 6 CO2 + 6 H2O + light E --> C6H12O6 + 6 O2 (= photoautotrophy). Photosynthesis takes place in the chloroplasts. Chloroplasts are mostly found in plants' leaves, but all green parts of plants have them. CO2 enters the leaf and O2 leaves via stomata (singular = stoma), microscopic pores in the leaf. H2O is delivered from the plant's roots.

The major differences between plant and animal cells

Plant cells have the following features that do not exist in animal cells: Plastids/chloroplasts are photosynthetic organelles. Recall that they originated from free-living cyanobacteria that were engulfed by a larger cell. Central vacuoles are prominent organelles in older plant cells. They have the same functions as lysosomes in animal cells - including storage and breakdown of wastes/macromolecules. Enlargement of the vacuole is a major mechanism for plant growth. Cell walls outside the cell membranes maintain the cells' shape and protect the cell from mechanical damage. Remember these are completely different from prokaryotic cell wall; plant cell walls are made of polysaccharides, cellulose, and protein.

Examples of organisms that can carry out photosynthesis

Primary producers/photoautotrophs such as plants, algae, and cyanobacteria.

What vascular tissue is and how having or not having vascular tissue ultimately affects the overall structure of a plant

Vascular plants can be divided into the seedless vascular plants and seed plants. Seedless vascular plants Seedless vascular plants include lycophytes and pterophytes. Seedless vascular plants still rely on water for reproduction (those sperm have to be able to swim!), and thus must live in damp places. However, vascular tissue allows them to grow tall! Additional Adaptations: Lycophytes are the most ancient land plant with roots for absorbing water and minerals. They also have microphylls, unusual leaves unique to lycophytes. Leaves increase the surface area of the plant, allowing it to perform more photosynthesis. Pterophytes include horsetails, whisk ferns, and ferns. Ferns are the only seedless vascular plant with well-developed leaves. Seedless vascular plants were the first plants to grow tall. Lignin gave them structural support and allowed for transport of substances throughout the plant. Roots anchored the plants and allowed absorption of water and nutrients; leaves increased surface area for photosynthesis. When seedless vascular plants grew tall, it dramatically decreased the amount of CO2 in atmosphere. CO2 levels dropped by a factor of five in Carboniferous period, resulting in global cooling and glacier formation. Dead plants did not decay in stagnant waters and became peat. This peat was later covered by sea, and over millions of years, heat and pressure converted it into coal. We now burn that coal, putting CO2 back into the air, which contributes to global warming (which seems ironic, but this is the carbon cycle :)). Seed plants Seed plants represent the vast majority of living plant species and include gymnosperms and angiosperms

-Produce oxygen. The O2 produced comes from the splitting of water during photosynthesis. It is cyanobacteria that originally gave the atmosphere enough O2 to support aerobic organisms. Without oxygenic photosynthesis, we would die! -Build and hold soil. De-vegetation leads to soil erosion and loss of soil (a finite resource) and nutrients. hold water and moderate climate. -Plants keep water from running off, provide shade (which reduces temperature), and reduce the impact of wind. -Are primary producers.

produce oxygen. The O2 produced comes from the splitting of water during photosynthesis. It is cyanobacteria that originally gave the atmosphere enough O2 to support aerobic organisms. Without oxygenic photosynthesis, we would die! build and hold soil. De-vegetation leads to soil erosion and loss of soil (a finite resource) and nutrients. hold water and moderate climate. Plants keep water from running off, provide shade (which reduces temperature), and reduce the impact of wind. are primary producers.