Plant cells are known as the fundamental building blocks of all plants. Both plants and animals have eukaryotic cells, which means they have a membrane-bound nucleus and cell organelles. Despite both being eukaryotic cells, there are several differences between them, and one such difference is plastids, which are not seen in animal cells. These plastids are double-membraned cell organelles that play an important role in producing and storing food in plants. Plastids are classified into three types:
- Chromoplasts are color plastids found in all flowers and fruits, primarily responsible for various colors.
- Chloroplasts are green-colored plastids containing green-colored pigments called chlorophyll within the plant cell.
- Leucoplasts are colorless plastids primarily employed to store carbohydrates, lipids, and proteins inside the plant cell.
This article will educate students on chloroplasts and their functions, which are vital for the CBSE Class 11 Biology Examination. Students must thoroughly prepare for this topic using the NCERT Solutions for Class 11 Biology and smart preparation strategies!
CBSE Class 11 Biology: Chloroplast
The term chloroplast came from the Greek words “khloros” (green) and “plates” (formed). These are the organelles present in plants that execute mainly the process of photosynthesis.
“A chloroplast is an organelle in green plants and algae containing the photosynthetic pigment, known as chlorophyll, which absorbs sunlight and transforms it into usable energy, releasing oxygen from water.”
Chloroplasts are sometimes referred to as the “cell’s kitchen.” It is because they produce and preserve food for the plant.
Chloroplasts are circular, oval, or disk-shaped structures in plants that aid in producing and storing food and energy. Their primary function is to absorb and convert sunlight into useable energy. They can be found in green leaves and stems, but they are most abundant in the parenchyma cells of the leaf mesophyll. They feature a biconvex lens-like structure and are surrounded by a two-layered envelope. They are composed of smaller sections called thylakoids, grouped in stock-like formations known as grana. In the chloroplast matrix, there are 40-80 grana. Refer to NCERT Solutions for Class 11 Biology for further information on the topic.
Chloroplast is a triple membrane-bound, a green pigment, saclike cell organelle that mainly focuses on photosynthesis (a biochemical mechanism that transforms solar energy into chemical energy for the growth and development of the plant).
CBSE Class 11 Biology: Functions of Chloroplast
Chloroplasts perform photosynthesis. The primary function of chloroplast is to provide a venue for light-dependent and light-independent reactions. Inorganic substances (carbon dioxide), water, and solar energy are transformed into food, i.e. glucose or carbohydrates (a sugar molecule). As a result, these cell organelles are essential for photosynthetic plants and algae to produce their food and not rely on other organisms for survival.
Because oxygen is a byproduct of photosynthesis, chloroplasts are an important site for creating this gas, which is then discharged from the cell into the environment. Oxygen is biologically significant due to its function in various physiological and biochemical processes in animals and other complex species. Students must check the NCERT Solutions for Class 11 Biology for better clarity of concepts.
Chloroplasts can roam around within the plant cell to locate the ideal area to absorb light energy. That’s similar to people going to the seashore to soak up the sun.
- The process of photosynthesis occurs in chloroplasts present in the leaves of the green plants and algae. Chloroplast performs various light-dependent and light-independent reactions that capture solar energy and convert it to chemical energy.
- Chloroplast components are involved in a variety of cell regulatory processes and photorespiration.
- Chloroplasts also support plant cells’ metabolic processes, such as creating fatty acids, isoprenoids, membrane lipids, starch, tetrapyrroles, and hormones.
- The chloroplasts are the primary organelles involved in pathogen defence, with the nucleus, cell membrane, and ER (endoplasmic reticulum).
- Chloroplasts have the potential to function as cellular sensors.
CBSE Class 11 Biology: Structure of Chloroplast
The chloroplast structure is enclosed by two 9-10 mm thick unit membranes. These membranes are separated by a space known as the periplast ideal space. Structurally, a chloroplast is split into two different parts, the grana, and stroma.
Grana are made up of thylakoids, which are disc-shaped structures. The chloroplast’s grana comprise chlorophyll pigments and serve as the receptors for sunlight responses.
The stroma, also known as the matrix, is a homogeneous matrix containing grana and is similar to the cytoplasm of cells in which all cell organelles are embedded. Stroma also contains enzymes, DNA, RNA, ribosomes, and other materials. Stroma lamellae aid in the connection of thylakoid sac stacks. Use NCERT Solutions for Class 11 Biology.
|Did You Know?
As per scientists, one cubic millimetre of a leaf could contain up to 500,000 chloroplasts. That equates to millions of chloroplasts in a single plant.
The chloroplast structure is made up of the following components:
Outer membrane: It is a semi-porous membrane permeable to tiny molecules and ions and allows for easy diffusion. Larger protein complexes cannot pass through the outer membrane.
Intermembrane Space: This is a narrow intermembrane space between the chloroplast’s outer and inner membranes, usually 10-20 nanometers wide.
Inner membrane: The chloroplast’s inner membrane forms a barrier to the stroma. It controls the flow of materials to and from the chloroplast. In addition to regulatory action, the inner chloroplast membrane synthesises fatty acids, lipids, and carotenoids.
Stroma: This protein-rich alkaline aqueous fluid is found within the inner chloroplast membrane. The stroma is the space outside of the thylakoid membrane. The stroma contains chloroplast DNA, starch granules, chloroplast ribosomes, the thylakoid system, and numerous proteins.
Thylakoid System: The stroma contains the thylakoid system. The system is made up of membranous sacs known as thylakoids. The chlorophyll is present in the thylakoids and serves as the site for the absorption of sunlight for the process of photosynthesis to occur. The thylakoids are grouped in grana, which are stacks of thylakoids. Each granum comprises between 10 and 20 thylakoids.
Chloroplasts contain chlorophyll, a green pigment that helps in absorbing light energy. These vital organelles can be found in all green tissues of plants, but they are particularly abundant in the parenchyma cells of leaves.
Chloroplast is one of the plant cell organelles containing chlorophyll (the substance that gives plants their green colour) and is responsible for photosynthesis, allowing plants to turn sunlight into energy. Thus, without chloroplasts, plants won’t be able to produce energy and food, and without these green plants, humans would go hungry and vanish. Hence one can rightly say that chloroplast is essential for the survival of, growth and development of both plants and animals. Students must have a good grasp of the topic. Students must analyse the NCERT Solutions for Class 11 Biology AESL. They must strategically plan their CBSE Class 11 Biology syllabus to pass the Biology subject with flying colours!