Question

Which is the most accurate description of how plants grow? a. by the addition of new cells at meristems that include stem cells b. by cell enlargement as the result of water uptake c. by both the addition of new cells and cell expansion d. by addition of fat cells e. by all of the above

Short answer

The most accurate description of how plants grow is by both the addition of new cells and cell expansion.

Step-by-step solution

Understanding Concepts Involved

Before answering the question, it is necessary to understand the key concepts involved. Meristems are tissue in plants consisting of undifferentiated cells (meristematic cells) capable of division. Stem cells are kind of 'master cells' that are able to change into any one of the body's more than 200 cell types. Cell enlargement refers to the increase in the size of a cell. This enlargement usually happens through the uptake of water into the plant's cells. Fat cells, or adipocytes, store fat but they are primarily observed in animals.

Analyze Each Option

Next, each answer option is evaluated based on the concepts learned. Option a emphasizes new cell addition at meristems, including stem cells, which is a valid point since meristems are a primary source of new cells in plants. Option b highlights cell enlargement due to water uptake, which is another aspect of some plant cells. Option c combines the concepts of options a and b, stating that plants grow by both addition of new cells and cell expansions. Option d mentions the addition of fat cells, which is incorrect as fat cells are predominant in animals. Option e indicates that all of the mentioned options are correct, which is untrue since option d is incorrect.

Selection of the Correct Answer

Finally, based on the analysis, the question asks for the most accurate description of how plants grow. Both the addition of new cells (especially at meristems that include stem cells) and cell enlargement resulting from water uptake play a significant role. Therefore, the most accurate description would be a combination of both processes. Thus, the correct answer is Option c - by both the addition of new cells and cell expansion.

Key concepts

Meristems

Meristems are special regions in plants where growth occurs. Think of them as growth factories where new cells are constantly being produced. These regions are found at the tips of roots and shoots, which makes sense since plants need to grow both upwards towards the sun and downwards into the soil.
Meristems consist of undifferentiated cells known as meristematic cells. These cells are unique because they have not yet been assigned a specific role in the plant. This allows them to divide and create new cells, some of which can specialize into different types of plant tissue.
Because of their ability to generate new cells, meristems are crucial for the continuous growth of plants. Without them, plants wouldn't be able to grow new stems, leaves, or roots, making it impossible for the plant to mature and thrive.

Stem Cells in Plants

Stem cells in plants are comparable to human stem cells in that they have the potential to develop into various cell types. In plants, these stem cells are usually found in the meristems.
The primary function of plant stem cells is to aid in growth. They achieve this by dividing continuously to add new cells. This process is important because it not only allows for the growth of new plant organs but also helps plants heal from injuries.
When a plant encounters damage or needs to grow a new leaf, its stem cells come into play. They can differentiate into the specific type of cell required to replace or grow new plant parts. This ability is vital for the plant's survival and adaptation to its environment.

Cell Enlargement

Cell enlargement is another key aspect of plant growth. This process occurs when individual plant cells increase in size. Unlike animals, plants often grow larger by expanding the size of their cells rather than increasing the number of cells.
A major factor in cell enlargement is water uptake. As a plant absorbs water through its roots, the water fills the cells, causing them to expand. This doesn't just make the cells larger, but it also helps the plant stand upright and reach for light.
Additionally, the cell wall's flexibility plays a significant role in how much the cell can enlarge. Some plant cells can expand up to 100 times their original size, thanks to water uptake combined with cell wall elasticity.

Water Uptake in Plants

Water uptake is fundamental for plant growth and survival. Without water, plants would not be able to transport nutrients, maintain their structure, or grow.
Plants absorb water primarily through their roots. These roots extend deep into the soil to access moisture. Once inside the plant, water moves through the xylem, a special tissue designed to transport water from the roots to the rest of the plant.
Through a process known as osmosis, water enters the cells and helps them enlarge. This increased cell size is crucial for the plant’s growth. Additionally, the transported water helps keep the plant cool and supports photosynthesis, the process plants use to convert sunlight into energy.