Question

A group of scientists studying vegetation in a mountain range observe that a certain flowering plant grows taller at lower elevations and shorter at higher elevations. Assuming the two populations of plants are genetically similar, those height variations are most likely due to developmental flexibility that allows the plants to assume tall or short growth forms. (a) Identify THREE biotic or abiotic factors that could differ at high and low elevations and cause the difference in plant height. (b) Using one of the factors listed in part (a) as an independent variable, write a hypothesis that proposes how this variable could cause the difference in plant height at high and low elevations. (c) You are given seeds for this species of plant. Design a procedure for a controlled experiment to test your hypothesis. (d) Describe the results that would support your proposed hypothesis, and the results that would refute your hypothesis.

Answer 1

Plant height variations observed at different mountain elevations may be due to abiotic factors like temperature, soil quality, and sunlight. A hypothesis could be that increased sunlight at lower elevations enhances photosynthesis, leading to taller growth. A controlled experiment varying sunlight while keeping other factors constant could test this hypothesis, with taller plants under higher sunlight supporting it.

Step-by-step explanation:

The height variations in the flowering plant species observed at different elevations can be attributed to various abiotic factors that differ at high and low elevations. Three such factors could be:

• Temperature: Higher elevations tend to have lower temperatures, which could influence plant metabolism and growth rates.
• Soil quality: Variations in nutrient content, pH, and composition might be significant at different elevations, affecting plant height.
• Amount of sunlight: Lower elevations may receive more intense sunlight, influencing photosynthesis and plant growth.

A hypothesis based on one of these factors could be: "Plants at lower elevations grow taller than those at higher elevations due to increased sunlight at lower elevations enhancing photosynthesis and promoting growth."

To test this hypothesis, a controlled experiment could be designed:

1. Plant seeds of the species from both elevations in identical controlled environments with varying levels of artificial sunlight consistent with the differences observed in their natural habitats.
2. Maintain all other conditions, such as temperature, water, and soil quality, constant to ensure that the independent variable, sunlight, is solely affecting growth.
3. Measure the plant height at maturity and compare results between the different sunlight treatments.

Results supporting the hypothesis would show that plants exposed to lower elevation sunlight intensities grow taller, similar to their natural low-elevation counterparts. Conversely, results that refute the hypothesis would occur if there is no significant difference in plant height regardless of sunlight intensity, suggesting that other factors are responsible for height variations.

Answer 2

Well, first of all, the question asks us to to list three different factors that could lead to this variation.

The first one is pressure, so, what happens is that, when the pressure changes with the height change, these plants develop in different ways. The second one is the oxygen, as we know, oxygen in higher elevations is less than in ocean elevation for example, so this can be a reason for this variation. The last one is the quantity of organic material on the soil, this can influence directly on the development of this population.

With that said, we need to write a hypothesis for one of these factors, let's choose the organic material because it's easier and cheaper to test. For that, the hypothesis is that, with less organic material available on the ground, the plant will grow smaller than on a normal soil. To test that, we need to grab samples of this flowering plant and put it at the same conditions as on the mountain, that is a possibility on a good lab, so after that, we'll change the quantity of organic material on some samples, to check if my hypothesis is right or not.

The positive results are that this is the reason why the plants grow smaller, so, with less organic material, the plants won't develop in the same way as it would happen with enough organic material. The negative results are that this is not the reason why these variations exist, so we need to test another factor to check why this variation is happening.