Question 1

An example of a mutualistic association between a plant and a fungus would be

Accepted Answer

Mycorrhizae is a mutualistic association between plant roots and fungi, in which the fungi provide the plant with increased nutrient uptake while receiving carbohydrates from the plant. Nitrogen fixation (A) involves a relationship between bacteria and plants, while Rhizobium infection (B) specifically refers to a bacterial infection of legumes. Parasitic infection (D) is a harmful association, not a mutualistic one.

Question 2

Which of the following is a primary difference between ectomycorrhizae and endomycorrhizae?

Accepted Answer

The primary difference between ectomycorrhizae and endomycorrhizae is that ectomycorrhizae do not penetrate root cells, instead they grow around the cells, while endomycorrhizae grow into invaginations of the root cell membranes.

Question 3

Nitrogen fixation is a process that

Accepted Answer

Nitrogen fixation is the process of converting atmospheric nitrogen gas (N2) into a usable form such as ammonia (NH3) or nitrate (NO3−). Therefore, the best choice is D, which states that nitrogen gas is converted into ammonia.

Question 4

In what way do nitrogen compounds differ from other minerals needed by plants?

Accepted Answer

Unlike other minerals, nitrogen requires the action of nitrogen-fixing bacteria to be made available to plants. Other minerals can be directly absorbed by plants through root hairs.

Question 5

Some botanists argue that the entire plant should be considered as a single unit rather than a composite of many individual cells. Which of the following cellular structures best supports this view?

Accepted Answer

Plasmodesmata are channels that connect the cytoplasm of neighboring plant cells. These channels allow for communication and transport of molecules between cells, making the plant a cohesive unit rather than a collection of individual cells.

Question 6

Which of the following would be the most effective strategy to remove toxic heavy metals from a soil?

Accepted Answer

Adding plant species that have the ability to take up and accumulate heavy metals (also known as phytoremediation) is the most effective strategy to remove toxic heavy metals from soil. These plants can then be harvested and disposed of properly, effectively removing the heavy metals from the soil. Heavy irrigation may cause runoff and spread the contamination to other areas. Fertilizers do not address the issue of heavy metal uptake and may even exacerbate the problem. Inoculating soil with mycorrhizae does not necessarily prevent heavy metal uptake by plants.

Question 7

Which of the following plant structures shares the most common features and functions with a fungal hyphae?

Accepted Answer

Root hairs and fungal hyphae share common features and functions, such as increasing the surface area for absorption and nutrient exchange. Both structures are also thin and elongated, allowing for efficient movement through soil or other substrates. Stomata are structures found on the surface of leaves and function in gas exchange, vascular cambium is responsible for secondary growth in woody plants, and lenticels are small pores found in the bark of woody stems for gas exchange. None of these structures share as many common features and functions with fungal hyphae as root hairs.

Question 8

The Casparian strip in plant roots is correctly described by which of the following?

Accepted Answer

The Casparian strip is a specialized layer of cells that surrounds the cells of the root cortex and blocks the movement of water and dissolved substances between cells. As a result, all water and dissolved substances that enter the stele must pass through a cell membrane, which allows for selective uptake of nutrients and minerals. This helps to ensure that only necessary minerals are absorbed from the soil, rather than all minerals in equal amounts. Therefore, choice D is the correct option.

Question 9

Pine seedlings grown in sterile potting soil grow much slower than seedlings grown in soil from the area where the seeds were collected. This is most likely because

Accepted Answer

The normal symbiotic fungi, known as mycorrhizae, are not present in the sterilized soil, which could lead to slower growth due to reduced water and mineral uptake. Additionally, sterilization may also kill the root hairs as they emerge, further reducing growth.

Question 10

Rhizobia, actinomycetes, and cyanobacteria all share the common feature that they can

Accepted Answer

Rhizobia, actinomycetes (specifically those in the genus Frankia), and cyanobacteria are all capable of fixing atmospheric nitrogen, converting it into a form that plants can use.

Question 11

A plant developed a mineral deficiency after being treated with a fungicide. What is the most probable cause of the deficiency?

Accepted Answer

The answer of A plant developed a mineral deficiency after...

Question 12

The earliest vascular plants on land had underground stems (rhizomes) but no roots. Water and mineral nutrients were most likely obtained by

Accepted Answer

Vascular plants in early evolution formed a symbiotic relationship with fungi known as mycorrhizae. The fungi colonized the root-like structures of plants, such as rhizomes, and helped to absorb water and essential minerals from the soil. This enabled the plants to grow taller and possibly led to the development of true roots. Therefore, absorption by mycorrhizae would have been the most likely way for early vascular plants to obtain water and essential nutrients.

Question 13

Upregulation of leghemoglobin biosynthesis in a leguminous species would most likely indicate

Accepted Answer

Leghemoglobin is a protein found in the nodules of leguminous plants that is involved in nitrogen fixation. Upregulation of leghemoglobin biosynthesis would suggest the successful inoculation of nitrogen-fixing bacteria, which form a symbiotic relationship with leguminous plants to provide them with fixed nitrogen.

Question 14

What are epiphytes?

Accepted Answer

Epiphytes are plants that grow on other plants but do not obtain nutrients from their hosts. They usually use the host plant only for support and are able to uptake nutrients and water from the atmosphere and rain. Examples of epiphytes include orchids, bromeliads, and ferns.

Question 15

A water molecule could move all the way through a plant from soil to root to leaf to air and pass through a living cell only once. This living cell would be a part of which structure?

Accepted Answer

The endodermis is a specialized layer of cells in roots that controls the passage of water and nutrients from the soil into the vascular system of the plant. The Casparian strip is a band of waterproof material that surrounds each cell in the endodermis and helps regulate the movement of water and solutes. A guard cell is a specialized cell in the epidermis that controls the opening and closing of stomata, which are pores on the surface of leaves that allow for gas exchange. The root epidermis is the outermost layer of cells in roots, which serves as a protective barrier and helps absorb water and nutrients from the soil. Therefore, the endodermis is the only structure that could contain a living cell through which a water molecule could move just once in its journey through a plant.

Question 16

Hyphae form a covering over roots. These hyphae create a large surface area that helps to do which of the following?

Accepted Answer

Hyphae form a mycelium around plant roots to create a large surface area that aids in the absorption of minerals and ions from the soil. This increases the availability of essential nutrients for the plant.

Question 17

Why is nitrogen fixation an essential process?

Accepted Answer

Plants require nitrogen to grow, but they cannot directly use the nitrogen gas in the atmosphere. Fixed nitrogen, such as ammonia or nitrate, is more accessible to plants. However, fixed nitrogen is often the limiting factor in plant growth because it is not always readily available in the soil. Nitrogen fixation is important because it adds fixed nitrogen to the soil, making it more available for plants to use.

Question 18

Carnivorous plants have evolved mechanisms that trap and digest small animals. The products of this digestion are used to supplement the plant's supply of

Accepted Answer

Carnivorous plants primarily rely on photosynthesis for energy and carbohydrates. However, they often grow in nutrient-poor soil and have evolved to supplement their mineral supply by digesting small animals.

Question 19

Root hairs are most important to a plant because they

Accepted Answer

Root hairs increase the surface area for absorption, allowing plants to absorb water and nutrients more effectively from the soil. While anchoring the plant and storing starches are important functions of roots, neither of these are specific to root hairs. Nitrogen-fixing bacteria typically inhabit the root nodules of legumes, not the root hairs.

Question 20

A rootless, green plant is found growing on the branches and trunks of rain forest trees, but lacks any apparent adaptation for collecting rainwater. This plant is most likely

Accepted Answer

The answer of A rootless, green plant is found growing...

Quiz 29: Resource Acquisition, Nutrition, and Transport in Vascular Plants