1. What is a chloroplast? Explain how a root of a plant, that lacks Chloroplasts, gets energy. What organelles are involved with converting the energy for the roots?
2. Explain why animal cells do not require a cell wall or a central vacuole.
A chloroplast is an organelle found in plant cells that is responsible for photosynthesis, the process of converting light energy into chemical energy. Without chloroplasts, a root of a plant would not be able to produce energy from light and would instead rely on other sources of energy. The root would obtain energy from the breakdown of carbohydrates, proteins, and lipids, which are stored in the cell. This energy is converted into a usable form by the mitochondria, which are organelles that are responsible for the production of ATP, the energy currency of the cell. The ATP is then used to power the metabolic processes of the cell.
Animal cells do not require a cell wall or a central vacuole because they do not need the structural support that a cell wall provides. Animal cells are able to maintain their shape and integrity through the cytoskeleton, which is a network of proteins that provide structural support. Animal cells also do not need a central vacuole because they do not need to store large amounts of water or other substances like plant cells do.
1. A chloroplast is a specialized organelle found in plant cells that is responsible for photosynthesis. It contains a pigment called chlorophyll, which captures light energy from the sun and converts it into chemical energy in the form of glucose.
The roots of a plant do not possess chloroplasts, so they cannot directly perform photosynthesis to obtain energy. Instead, the roots rely on other mechanisms to acquire energy. Plants have specialized structures called root hairs, located on the surface of the roots, that increase their absorption capabilities. These root hairs have a large surface area, allowing them to efficiently absorb water and minerals from the soil.
Within the roots, the energy is obtained through a process called respiration. The process of respiration occurs in the mitochondria, which are organelles found in all cells, including plant cells. Mitochondria are responsible for converting glucose (obtained from the leaves or storage organs of plants) into energy in the form of adenosine triphosphate (ATP) through a series of chemical reactions.
Therefore, while the roots lack chloroplasts for photosynthesis, they can rely on the process of respiration occurring in the mitochondria to convert stored glucose into usable energy.
2. Animal cells do not require a cell wall or a central vacuole because they have evolved different mechanisms to meet their structural and functional needs.
Cell walls, which are found in plant cells, provide rigidity and support to the cell. In plants, the cell wall is mainly composed of cellulose, which forms a protective layer around the cell membrane. Animal cells do not possess a cell wall because their structural integrity and shape are mainly maintained by a combination of the cytoskeleton (composed of protein filaments) and the extracellular matrix (a network of proteins and other molecules outside the cells).
Similarly, plant cells contain a large central vacuole that helps regulate cell turgidity, store water, and various substances. However, animal cells have smaller and scattered vacuoles, usually known as vesicles, which perform specific functions such as transportation, storage, and excretion of cellular substances.
Since animal cells do not rely on the support provided by a cell wall and have different mechanisms to regulate internal pressure, they do not require a cell wall or a central vacuole. The absence of these structures allows animal cells to have greater flexibility, mobility, and adaptability in their environment.
1. A chloroplast is an organelle found in plant cells and some algae. It is responsible for the process of photosynthesis, where light energy is converted into chemical energy in the form of glucose. Chloroplasts contain a green pigment called chlorophyll, which captures sunlight and uses it to power the synthesis of glucose.
In plants, the majority of photosynthesis occurs in the leaves, particularly in the specialized cells called mesophyll cells, which contain chloroplasts. However, the roots of plants do not have chloroplasts, so they cannot directly produce energy through photosynthesis.
Instead, roots obtain energy through a process called respiration. Respiration occurs in specialized organelles called mitochondria, which are present in almost every cell, including the cells of plant roots. Mitochondria convert glucose obtained from the soil into ATP (adenosine triphosphate), which is the main energy currency of the cell.
The process of respiration involves breaking down glucose in the presence of oxygen to release energy. The energy released is then used by the root cells for various metabolic functions like active transport, cellular division, and growth.
2. Animal cells do not require a cell wall or a central vacuole for several reasons:
a) Support and shape: Animal cells have a flexible cytoskeleton made up of proteins like actin and microtubules, which provide structural support and help maintain cell shape. This allows animal cells to maintain their shape without the need for a rigid cell wall.
b) Mobility: Unlike plants, animals are capable of locomotion. A cell wall would restrict the movement of animal cells. Without a cell wall, animal cells can change shape and move as needed.
c) Osmoregulation: The central vacuole in plants plays a crucial role in regulating water balance and maintaining turgidity. In contrast, animal cells maintain water balance through specialized structures like kidney cells and excretory systems, which allow for active regulation of water and waste removal.
d) Specialized tissues and systems: Animals have developed complex tissues and organ systems to perform specific functions efficiently. The absence of a cell wall and central vacuole allows for more flexibility in cell specialization. Animal cells can form tight junctions, desmosomes, and gap junctions to provide structural integrity and communication between cells.
Overall, the absence of a cell wall and central vacuole in animal cells is due to the unique adaptations and requirements for mobility, specialized tissues, and regulatory mechanisms that are characteristic of animals.