Biology Exam 2 Content Review Flashcards
What are characteristics that all plants share?
All plants have some form of chlorophyll or beta carotene, store starch as an energy products, have chloroplasts, and a flexible cell membrane.
What cell structure do all land plants have?
All land plants have a cellulose cell wall outside of the flexible cell membrane for greater protection and structural support.
How did plants evolve?
Plants evolved from the water to live on land.
What contributed to the evolution of plants on land?
Plants started off as completely aquatic. However, there were a lot of limitations associated with living underwater. There was the limited amount of sunlight/wavelengths that could reach plants, because water absorbed a lot of the light energy. Natural selection favored plants that were living more closely to the surface of the water because those plants could get more sunlight than the plants that were further underwater. Plants need CO2 to perform photosynthesis, but CO2 is far less available underwater than it is in the air. It takes a lot of time for CO2 to diffuse down to the plants underwater. Thus, again, natural selection favors plants that live closer to the surface of the water because they don’t have to wait as long for CO2 to diffuse down to them (compared to the plants that live in deeper waters). Lastly, at the time that plants were evolving to live on land, there weren’t any major heterotrophs to consume those plants before they got the chance to develop.
Why couldn’t plants just move onto land without any major adaptations?
Plants need water to grow and survive. Before the land, plants were surrounded by water all the time, so there wasn’t much need to develop complex water (and sugar) transportation systems. The water also allowed the plants to remain buoyant and reach as much sunlight as was possible in underwater conditions. However, on land, there was nothing supporting the plants to keep them upright. And without structural support, the plants wouldn’t be able to reach and obtain adequate amounts of sunlight to perform photosynthesis. Plants also used the water for sexual reproduction where the sperm would swim to the egg to fertilize it. But again, the drier environment would force the plants to develip new ways of reproducing.
List the 5 Major Plant Phyla in Order of their Evolution
Chlorophyta, Bryophyta, Pteridophyta, Coniferophyta, and Anthophyta
List the taxonomic hierarchy in order from most to least exclusive.
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
What is the closest known ancestor to green land plants?
Chlorophyta
What were the oldest vascular land plants?
Ferns/Pteridophyta
How were Bryophyta able to survive on land without any vascular tissue?
The Bryophyta had cuticles that worked to prevent dehydration. They had stoma and lived in damp areas which allowed easier diffusion of water and nutrients, and used water to reproduce. So although they were able to survive on land, they weren’t really able to grow very tall because they didn’t have any vascular tissue.
What is vascular tissue?
Vascular Tissue are used to transport water and sugar/nutrients around the plant.
What are the first land plants?
Mosses are the first land plans but they aren’t the ancestors of higher/more complex land plants.
What is the limitation of Pteridophyta?
Pteridophyta are the first vascular land plants, allowing them to grow taller and reach more sunlight. However, they are limited because they must still sexually reproduce in moist environments. It wasn’t until the development of the gymnosperms that plants were able to reproduce outside of water.
What was the significance of gymnosperms in the evolution of plants onto land?
Gymnosperms were vascular, naked-seed plants. They were the first land plants that could reproduce without water/moist environments because of the innovation of the seed and pollen. The development of the seed helped to protect embryo against water loss & herbivory, permits dormancy, and prompted easier/vaster dispersal. The development of pollen (gametophyte) allowed plants to reproduce in dry conditions. Additionally, the Coniferophyta had cones (small ones for male and large ones for females) to protect female eggs.
What was the significance of angiosperms?
Angiosperms were plants with fruit-covered seeds and flowers. The fruit increased the protection of the embryo and the flowers helped better facilitate pollination by attracting animal pollinators (although there was a lot of wind and water pollination as well). Angiosperms include Anthophyta which are the most widely distributed group of all land plants. Additionally, most angiosperms plants are annuals and herbaceous.
What are the divisions of Anthophyta?
Anthophyta are separated into monocots and dicots.
Annuals vs. herbaceous
Annuals - the plant dies off at the end of the year and leaves only the seeds for the next growing season.
Herbaceous - the plant is short-lived and non-woody
What is a monocot?
A type of angiosperm that produces 1 leaf at germination, has scattered vascular bundles, parallel leaf veins, and flower petals in multiples of 3.
What are dicots?
Dicots are angiosperms that have 2 leaves at germination, a circular arrangement of vascular bundles, branching leaf veins, and petals in multiples of 4 or 5.
What are the small membrane layers in the chloroplasts called? And what is their significance?
The Thylakoid are stacked and flattened vesicles in the chloroplasts that help facilitate photosynthesis. There’s small spaces between the thylakoids that allow them to maximize surface area and contribute to more efficient extraction of radiant energy.
Why are roots important?
Roots provide moisture and inorganic nutrients to the plant. They help attach the plant to the ground and support it as it grows vertically to reach more sunlight. Tuber roots (like carrots and sweet potatoes) store starch for the plant. And the snorkel roots give more access to oxygen.
What is the tap root system?
Tap roots have a long central shaft to store nutrients. They reach deeper into the soil to reach deeper water tables. They are limited by shallow soils, which could hinder their ability to grow and access water. Dandelions are examples of tap roots. (They are hard to get rid of because the roots extend very far into the soil, so unless you dig out the root completely, the dandelions will continue to grow).
What is the Fibrous/Diffuse Root System?
Has shorter roots that fan out into a mesh-like structure. Their primary function is to support the plant and allow access to a more shallow water supply
What are tuber roots?
Tubers (like sweet potatoes) are swollen masses that store energy.
What are snorkel roots?
aka Pneumatophores; They roots emerge below ground but rise above ground to obtain oxygen for respiration in the root. Snorkel roots are usually present in species that have roots in water saturated soil or standing water.
What’s the difference between roots and shoots?
Roots grow below ground. Shoot are the above-ground part of the plant.
What are the advantages and disadvantages of axial versus dendritic stems/trunks/shoots?
Axial shoots have a central column that all branches and leaves emerge from. They have the advantage of being able to withstand heavy snow, hail, and winds in harsher environments. Their disadvantage would have to be a smaller surface-area-to-volume ratio, which means they can’t perform as much photosynthesis as dendritic plants.
Dendritic shoots have sub-branching structure where branches emerge and there’s the emergence of more branches from those branches (there’s no real central column that they all attach to). Dendritic shoots have the advantage of creating a greater surface-area-to-volume ratio between leaves and allows them to obtain more sunlight and perform more photosynthesis consistently. Their disadvantage is that there can be a lot of breakage of branches due to strong winds, ice, hail, snow, and rain.
What is the p-value in statistics?
The p-value is the probability that the data matches randomness.
What are the 5 requirements of H-W equilibrium?
- Random mating
- No mutations
- No natural selection
- Large/infinite population size
- No gene flow
Explain H-W as a null hypothesis.
The null hypothesis states that in a given situation, randomness prevails - there is no relationship between variables in an experiment. H-W equilibrium states that allele frequencies don’t change outside of the range of what randomness would predict. Thus, because H-W depends on randomness, it can be considered a null hypothesis. The alternative hypothesis to H-W would be evolution: Evolution states that allele frequencies are changing outside of what randomness would predict. Thus, in a chi-square analysis of a population to determine if the population is in H-W equilibrium, a chi-square value that is greater than (or equal to) the critical value (under the correct degrees of freedom) will mean that we reject the null or H-W. (If the chi-square analysis of the population yields a chi-square value that is less that the critical value under the correct degrees of freedom, then you fail to reject the null/H-W and evolution is not occurring).
What is the decision-rule for chi-square analysis?
IF the chi-square value is greater than or equal to the critical value, then you reject the null hypothesis.
If the chi-square value is less than the critical value, then you fail to reject the nut hypothesis.
Why is surface-area-to-volume ratio important in plant processes?
A greater surface-area-to-volume ratio in plants allows for greater obtention of resources like water, nutrients and sunlight.
1. The spaces between the thylakoids in the chloroplasts create a greater surface-area-to-volume ratio in the chloroplasts, allowing for more sunlight to be absorbed and more photosynthesis to take place. (The reason leaves aren’t connected to each other is for this similar reason)
2. Plants’ root hairs have a large surface-area-to-volume ratio which allows them to absorb/take-up greater amounts of water and nutrients.
How do micelles function in soil to affect nutrient availability and uptake in plants?
Micelles are hardened mixed masses of clay and soil. They are positively charged on the inside, but are negatively charged on the outside. The outside negative charge attracts positively charged ions of nutrients like sodium, potassium, and magnesium. But these are also nutrients that plants need to live and grow. So the micelles are causing a decrease in the availability of nutrients that the plant can use.
How do acids in soil affect nutrient uptake in plants?
In very fine, caly soils, acids have positively charged H+ ions and these H+ ions have a greater affinity for the negatively charged micelles than the other positively charged nutrients. So the addition of acids to the soil increases the H+ ions. And the H+ ions attract to the micelles and take up all the available attachment sites, leaving the other positively charged nutrients free to be taken up by the plants.
In tropical soils, microbes’ rapid decomposition generates, in effect, acids. These acids lower the soil pH, and lower soil pH as well as very frequent, and heavy precipitation, causes the leaching away of nutrients - it decreases the availability of nutrients in the soil and decreases nutrient uptake in plants.
In very sandy soils, with or without lower pH, leaching away can occur because of how easily water passes through.
What are the 5 taxonomic kindgoms?
- Monera
- Protista
- Plantae,
- Fungi
- Animalia
What are the 3 Domains?
- Bacteria
- Archaea
- Eukarya
