Transcript
Pre-Lab Questions
When did vascular plants evolve? How was this timeline uncovered?
In the Silurian era, the oldest known vascular plants appeared, and in the Devonian period, the oldest known bryophytes. Fossil examinations and even phylogenetic studies that place species in their proper evolutionary timeline have found this.
How does a vascular system help a plant to grow bigger?
- The vascular system contributes to the transfer of food and water to the most essential parts of plants. No vascular tissues are found in thallophytes, such as phloem or xylem. Therefore, the plant body is not erect, so all areas of the plant can not be reached by water and food. These plants grow near water or moisture on the surface. Because of their ability to help move water and food to all regions, vascular plants may reach great heights.
In 2 - 3 sentences, discuss how gas exchange affects transpiration.
- The pores on the plant's epidermis through which gaseous exchange takes place are stomata. They are also the pores from which water evaporates from the plant and, from transpiration, this is lost. Water vapor is also released as the stomata open up to take in carbon dioxide, along with gas molecules. The perspiration would increase if the stomata were to open many times during the day. Transpiration can be decreased in cold climates or at night.
Describe one way in which plants can adapt to changes in water supply.
The plants respond to these conditions in dry climates where there is a lack of water, by opening their stomata for gaseous exchange at night. During the day, this helps minimize transpiration. Their stomata are also sunken, meaning they are deeply rooted in the thick layer of epidermis in order to prevent water loss.
Why is water referred to as the “universal solvent?”
As it dissolves more substances than any other liquid, water is regarded as a universal solvent. Water's chemical structure and physical properties make it a perfect solvent. Water has an oxygen and hydrogen polar structure, where oxygen has a negative charge and hydrogen has a positive charge. This structure enables water to become drawn to other molecules.
Why is a water droplet shaped like a sphere?
The shape of droplets of water is responsible for surface tension. Although the water droplet can be easily deformed, it appears to be pulled by cohesive surface force in spherical shape. All fluid would be roughly spherical if other forces such as gravity are absent. This form minimizes the surface layer's wall stress. Raindrops lose the rounded form and be like the top half of the hamburger bun as it falls.
In essay form, discuss three adaptations plants have made to thrive in different environments.
Three adaptations:
Plants have adapted unique features to survive in various environments. The explanation why some plants are present in certain areas but not in other areas is explained by these adaptations. The adaptation and its necessity will be demonstrated by the following three examples from different geographic regions.
Desert :
The desert is dry and the weather is hot throughout the day. The total annual rainfall is also much smaller than in other countries and rain is unpredictable. The rest of the year is dry and plants have a lot of sunshine reflecting on them. Soil is sandy and rocky, so it is not able to retain water and wind, so plants dry out, too. There have been many adaptations to deal with high temperatures and dry plants.
Succulents are certain plant types which store water in the stem or leaves.
Some plants have no leaves or small leaves, so it decreases water loss and allows them to go deep down and spread widely to absorb water via a long root system.
So, some plants have a short life cycle to escape drought.
Many plants have spines that avoid them from being eaten by animals for water.
Plants grow slower and have a waxy layer on the stem and other surfaces to minimize the loss of water.
Tropical Rainforest:
By raising the risk of flooding, leaching nutrients from the soil and harmful bacterial growth, heavy rainfall in tropical rainforests causes problems. So here, by using all the available nutrients from decomposed plants and animals that make the soil poorly stable, plants grow quickly. The forest is so thick that the forest soil can not be reached by sunlight. Yet 12 hours of strong light will thrive at the top of the rainforest in the canopy.
Waxy plant surfaces allow water to run away, preventing bacterial development, and stilt root enables water retention for plants.
Some plants ascend or grow on others in order to get sunlight.
Flowers are meant to attract animal pollinators since there is no wind to enable pollination.
Some have aerial roots to consume environmental minerals and water.The Temperate Grassland:
Summer is hot and winter is cold. Rainfall is not certain and a very common occurrence is drought. As it has organic matter that comes from dead grass, the soil is very fertile. For agriculture, these areas are common and few original plants now survive for a few days.
Also the above ground part dies out in the case of fire, the root survives to sprout again, and some have dense bark to withstand fire.
Plant roots go deep in the soil to absorb full water and it is impossible to take out the whole root through this extensive root system.
They take advantage of wind pollination and, during heavy wind, soft stems cause them to bend.
Experimental Results
Draw what you saw in the digital slides in the boxes provided below. Label the xylem and phloem.
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Show how far the dye traveled in the submerged and air-dried celery stalks by drawing on the images below.
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Post-Lab Questions
How far did the dye travel in the celery which was submerged in water for 15 minutes? How far did it travel in the piece which was air-dried for 15 minutes?
Owing to the fracturing of the water column, you can see the movement in the submerged and there is no movement in dry. In submerged celery, when transpiration takes place from the leaves, dye passes upward and we see the colored dots at the tip, that is, the colored dye water moving up, to the xylem plant tips.
In which celery stalk was the water column broken?
Dried celery has a column of broken water. This occurred because within the stem there is air, which is why water did not move across the celery slice.
Experiment 2: Water Movement in Flowers
Post-Lab Questions
Record your hypothesis from Step 3 here. Be sure to address how the dye will affect the flower over time, and why.
My hypothesis is that the longer the flower is in the dye the more colored it will get. I think this because as the flower needs more water it will take the colored water. The longer it takes the water the more color.
Show where the dye traveled in the flower after 24 and 48 hours and explain how it got there in the space provided.
It got there because as the plant lost water it wanted more so it soaks up the colored water which then eventually reaches the slower petals.
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What factors can influence the rate of transpiration in flowers?
Temperature, humidity, sunlight, wind
