Why was it logical to predict that amyloplasts function as statoliths? a. They are dense and settle to the bottom of gravity-sensing cells. b. They are present only in gravity-sensing cells. c. They make a direct physical connection with membrane proteins that have been shown to be gravity-receptor molecules. d. Their density changes in response to gravity.

Verified step by step guidance

1. Step 1: Understand the question. The question is asking why it was logical to predict that amyloplasts function as statoliths. Statoliths are organelles that help plants sense gravity. Amyloplasts are a type of plastid that stores starch and are known to be dense and settle at the bottom of cells.
2. Step 2: Analyze the options. Option a suggests that amyloplasts are dense and settle to the bottom of gravity-sensing cells. This is a characteristic of statoliths, making it a logical prediction for amyloplasts to function as statoliths.
3. Step 3: Evaluate option b. This option suggests that amyloplasts are only present in gravity-sensing cells. However, amyloplasts are found in all plant cells, not just gravity-sensing cells, so this option is not correct.
4. Step 4: Consider option c. This option suggests that amyloplasts make a direct physical connection with membrane proteins that have been shown to be gravity-receptor molecules. While this could potentially suggest a role in gravity sensing, there is no evidence to suggest that amyloplasts make such a connection, making this option incorrect.
5. Step 5: Evaluate option d. This option suggests that the density of amyloplasts changes in response to gravity. While this could potentially suggest a role in gravity sensing, there is no evidence to suggest that the density of amyloplasts changes in response to gravity, making this option incorrect. Therefore, the correct answer is option a.

Key Concepts

Amyloplasts

Amyloplasts are specialized organelles found in plant cells that store starch, a polysaccharide. They are a type of plastid and are particularly abundant in non-photosynthetic tissues, such as roots and tubers. Their dense nature allows them to settle under the influence of gravity, which is crucial for their proposed role in gravity sensing.

Statoliths

Statoliths are specialized structures that help organisms sense gravity. In plants, statoliths are typically dense particles, such as amyloplasts, that settle in response to gravitational forces. This settling triggers a physiological response in the plant, allowing it to orient its growth directionally, a process known as gravitropism.

Gravitropism

Gravitropism is the growth response of a plant to gravity, allowing it to orient its roots downward and stems upward. This phenomenon is mediated by gravity-sensing cells that detect the position of statoliths, which influence the distribution of growth hormones like auxins. Understanding gravitropism is essential for comprehending how plants adapt to their environment.