Plant Evolution
Explain what makes a plant a tracheophyte and why this was an important evolutionary development
Tracheophytes have vascular tissue, including xylem and phloem. This allows plants to transport water, minerals, and sugars through the plant and supports larger body sizes.
Explain what a gametophyte is and what role it plays in the plant life cycle.
A gametophyte is the haploid multicellular generation. It produces haploid gametes through mitosis.
Explain what a rhizoid does and why it is different from a true root.
Rhizoids anchor plants and help them stay attached to a surface, but they are not true roots and do not have the same vascular structure as roots.
Explain the role of the chloroplast in a plant cell and why it is important to plants.
Chloroplasts are the organelles where photosynthesis occurs. They capture light energy and use it to produce chemical energy/organic compounds that support the plant.
Explain the difference between seaweed and seagrass, even though both can be found in marine environments.
Seaweeds are algae and are not true plants. Seagrasses are true flowering plants that have vascular tissue, roots, stems, and leaves and are adapted to living underwater.
Explain how gymnosperms and angiosperms are related and what major feature they share
Both are seed plants and are more closely related to each other than to seedless plants. They both produce seeds, which protect the developing embryo and help reproduction occur without requiring the embryo itself to be exposed.
Explain the difference between an antheridium and an archegonium and why both are important.
An antheridium is the male gametangium that produces/protects sperm. An archegonium is the female gametangium that contains/protects the egg. They protect the reproductive cells from drying out and help organize reproduction.
Explain what sori are and what their role is in fern reproduction.
Sori are clusters of sporangia found on fern fronds. The sporangia produce spores through meiosis.
Explain the role of the mitochondrion in a plant cell.
Mitochondria carry out cellular respiration, which helps release usable energy from organic molecules for cellular processes.
Explain what a microphyll is and how it differs from a megaphyll.
A microphyll is a leaf with a single unbranched vein. Megaphylls have a more complex system of branching veins and are associated with plants such as ferns and seed plants.
Explain what lignin does for plants and why it was important for life.
Lignin strengthens plant cell walls and is especially important in vascular tissue. It provides structural support and helps plants transport water, allowing them to grow taller and larger.
Explain why a haploid spore can grow into a multicellular haploid gametophyte without changing its chromosome number.
The spore is haploid and undergoes mitosis. Mitosis produces genetically similar cells with the same chromosome number, allowing the spore to develop into a multicellular haploid gametophyte.
Explain the differences between parenchyma, collenchyma, and sclerenchyma cells.
Parenchyma cells are generally involved in functions such as photosynthesis and storage. Collenchyma provides flexible structural support. Sclerenchyma provides stronger, more rigid support because of thick, often lignified cell walls.
Explain what the central vacuole does and why it is especially important for plant cells.
The central vacuole stores water and other substances and helps maintain turgor pressure. Turgor helps keep plant cells firm and supports the plant.
Explain how you would distinguish the three major mangrove species discussed in class using their scientific names. And write their scientific names (red, black, and white)
Red- Rhizophora mangle. Long-arching prop roots, long bean-like seeds, yellow exclusion leaf
Black- Avicennia germinans. Small teardrop seeds, salt excretion on leaves
White- Laguncularia racemosa. Two smalls bumps (glands) at the base of the leaf on the stem.
Explain how the evolution of vascular tissue changed the way plants could live on land.
Vascular tissue allowed plants to move water and nutrients throughout their bodies rather than relying only on diffusion. Lignified vascular tissue also provided support, allowing plants to become larger and develop true roots, stems, and leaves.
Explain what happens during fertilization and why it changes the chromosome number.
Two haploid gametes combine during fertilization. Their nuclei fuse, producing a diploid zygote with two sets of chromosomes.
Explain what aerenchyma is and why it is useful to plants living in wet or oxygen-poor environment,.
Aerenchyma is tissue containing large internal air spaces. These spaces help move gases through the plant, which is especially useful when roots are surrounded by water and have limited access to oxygen.
Explain what plasmodesmata are and how they allow plant cells to communicate.
Plasmodesmata are channels connecting neighboring plant cells through their cell walls. They allow materials and signals to move between cells.
Draw a plant cell and its major components.
include:
-cell wall
-cell membrane
-plasmodesmata
-large central vacuole
-nucleus
-chloroplast
-mitochondria
-ER
-Golgi
Explain why bryophytes are generally limited in size compared with seedless vascular plants. Your answer should connect their vascular tissue, method of transport, and dominant life-cycle stage.
Bryophytes lack true lignified vascular tissue, so they rely heavily on diffusion for transporting water and nutrients, which limits how large they can grow. They also have a dominant gametophyte generation. Seedless vascular plants have lignified xylem and phloem, allowing more efficient transport and support, and their sporophyte generation is dominant.
Explain the complete sequence of the alternation of generations life cycle in plants, including where mitosis, fertilization, and meiosis occur.
A haploid spore grows by mitosis into a haploid gametophyte. The gametophyte produces haploid gametes by mitosis. Fertilization combines the gametes to form a diploid zygote, which grows by mitosis into a diploid sporophyte. The sporophyte undergoes meiosis to produce haploid spores, restarting the cycle.
Compare the structures and functions of rhizoids in bryophytes with true roots in ferns.
Bryophytes use rhizoids mainly for anchoring and do not have true vascular roots. Ferns have true roots containing vascular tissue, which allows them to absorb and transport water and minerals more effectively and contributes to their larger sporophyte bodies.
A plant cell is placed in a very concentrated saltwater solution. Explain what happens to the cell and why.
The outside solution is hypertonic, so water moves out of the cell. The central vacuole shrinks, turgor pressure decreases, and the plasma membrane/protoplast pulls away from the cell wall. This process is called plasmolysis.
Explain the advantages and disadvantages of unisexual versus bisexual gametophytes in bryophytes. What environmental conditions could favor each strategy?
Bisexual gametophytes- provide reproductive assurance when individuals are isolated because one individual can produce both types of gametes. BUT self-fertilization can reduce genetic variation and increase inbreeding.
Unisexual gametophytes- promote outcrossing and genetic mixing, BUT they require compatible individuals to be nearby and depend on sperm dispersal.