Fundamental Unit of Life

Mitochondria contain their own circular DNA molecule (mtDNA), separate from nuclear DNA. This mitochondrial DNA encodes proteins essential for the organelle's role in ATP production. The other organelles listed (golgi apparatus, ribosomes, vacuoles) do not contain DNA.

Lysosomes are single membrane-bound organelles containing digestive enzymes. The nucleus has a double membrane (nuclear envelope), mitochondria and chloroplasts also have double membranes, making lysosome the correct answer.

Eukaryotes have a well-defined nucleus enclosed by a nuclear membrane, separating genetic material from the cytoplasm. Prokaryotes lack a nuclear membrane and have their DNA free in the nucleoid region.

Rough Endoplasmic Reticulum (RER) appears rough under the microscope because ribosomes are attached to its outer surface. Ribosomes are the protein-synthesizing machinery that give RER its characteristic textured appearance.

Animal cells are of two types, eukaryotic, which contain a nucleus, and prokaryotic, which do not. Prokaryotes are single-celled organisms, while eukaryotes can be either single-celled or multicellular.

Osmosis is specifically the movement of water molecules across a selectively permeable membrane from a region of lower solute concentration to higher solute concentration. Diffusion refers to solute movement, plasmolysis is cell shrinkage in hypertonic solutions, and active transport requires energy.

Genes are the functional segments of DNA that code for specific proteins and determine hereditary traits. Chromosomes are structures containing many genes, RNA is a nucleic acid, and peptides are protein chains.

 The rod-shaped structures in the nucleus of a cell are chromosomes. They carry genetic material in a 'rod' of DNA that is bonded to various proteins in the cell nucleus.

Plasmolysis is the process where a plant cell's protoplasm shrinks away from the cell wall when placed in a hypertonic solution (high solute concentration outside), causing water to move out of the cell by osmosis.

In an isotonic solution, the solute concentration is equal inside and outside the cell, so there is no net movement of water. The cell neither swells (hypotonic) nor shrinks (hypertonic), remaining unchanged in size.

The primary cell wall of plants is composed of the polysaccharides cellulose, hemicellulose and pectin.

Cytoplasm is the jelly-like, water-based substance that fills the cell and surrounds organelles. It provides the medium for metabolic reactions and organelle movement.

Amoeba can change its shape due to its flexible cell membrane and cytoplasmic streaming, forming pseudopodia ('false feet') for movement and feeding. Plants have rigid cell walls, bacteria maintain fixed shapes, and algae have cell walls or structured forms.

Plant cells differ from animal cells in the presence of a large central vacuole.

ATP (Adenosine Triphosphate) is the primary energy currency of the cell, providing energy for cellular processes through hydrolysis of its high-energy phosphate bonds. DNA stores genetic information, genes code for traits, and ribosomes synthesize proteins but don't directly provide energy.

The nucleoid is the nuclear region in prokaryotic cells where the genetic material (DNA) is located, but it is not surrounded by a nuclear membrane. Nucleolus is found within eukaryotic nuclei, while vesicles and cisternae are membrane-bound structures in eukaryotes.

The nucleus contains the cell's genetic material (DNA) and controls all cellular activities, including growth, development, and protein synthesis, thereby determining how the cell develops and what form it takes. Vacuoles store materials, mitochondria produce energy, and plastids (in plants) have specific functions like photosynthesis or storage.

When plants are placed in water, the water enters their cells (this is because their sap has a strong solution). The water enters the plant through osmosis and fills up the cell with water to its maximum capacity. A strong cell wall stops the cells from bursting (as in animal cells) and makes the plant to become turgid (becomes rigid/stiff because of water).

The statement about eukaryotic cell membranes bearing respiratory enzymes is false. Respiratory enzymes are embedded in prokaryotic cell membranes where they perform electron transport. Eukaryotic cells perform respiration in mitochondria instead, with their membranes serving different functions like transport and signaling.

Leucoplasts are a category of plastid and as such are organelles found in plant cells. They are non-pigmented, in contrast to other plastids such as the chloroplast.

Chloroplasts are organelles found exclusively in plant cells and some algae, where they conduct photosynthesis. Ribosomes, nuclei, and plasma membranes are universal features found in both plant and animal cells.

The endoplasmic reticulum (ER) is a complex network of membrane-bound tubules and sheets that extends throughout the cytoplasm. It provides a large surface area for cellular activities like protein synthesis and lipid metabolism. Vacuoles are storage sacs, chloroplasts are for photosynthesis, and mitochondria produce energy.

Plastid is absent in an animal cell. The plastid is a major double-membrane organelle, found among others, in the cells of plants and algae.

Lysosomes are membrane-bound sacs containing digestive enzymes but lack DNA. Plastids (including chloroplasts) and mitochondria have their own DNA from their evolutionary origin as independent prokaryotes. The nucleus contains the main cellular DNA.

Option (1) is correct. Diffusion across the membrane is the net movement of molecules in a fluid from the region of higher concentration to the region of lower concentration. This is because it decreases the amount of free energy. Diffusion is a spontaneous process.

Mitochondria are called the powerhouse of the cell because they generate ATP through cellular respiration, releasing energy from organic compounds. Lysosomes digest waste, plastids (in plants) handle photosynthesis, and vacuoles are storage compartments.

Cytoplasm is the gel-like, jelly-like fluid that fills the cell and suspends organelles. It provides the medium where cellular processes occur and organelles are embedded or suspended. The nucleus is the control center, lysosomes digest waste, and vacuoles store materials.

Robert Hooke first observed and named 'cells' in 1665 while examining cork under a primitive microscope. He saw small box-like structures that reminded him of monks' cells. Schleiden and Schwann later formulated the cell theory, and Robert Brown discovered the nucleus.

Mitochondria are membrane-bound organelles found only in eukaryotic cells, absent in prokaryotes. Prokaryotes do have cell membranes, cytoplasm, and ribosomes (70S type). The lack of mitochondria is a key distinguishing feature of prokaryotic cells.

The plasma membrane is composed mainly of phospholipids (lipids) and proteins, arranged in the fluid mosaic model. Lipids form the basic bilayer structure, while proteins perform functions like transport, signaling, and enzymatic activity. Carbohydrates are present but are attached to proteins or lipids, not a major component.

Both prokaryotic and eukaryotic cells contain chromosomes carrying genetic material, though they differ in structure (circular vs linear) and location (nucleoid vs nucleus). Prokaryotes lack a nuclear membrane and have circular chromosomes. Respiratory enzymes on the cell membrane are a prokaryotic feature, not shared by eukaryotes.

Chloroplasts' main role is to conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight and converts it and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water. They then use the ATP and NADPH to make organic molecules from carbon dioxide in a process known as the Calvin cycle.

 Animal cells differ from plant cells in that, they do not have cell wall.

The Golgi apparatus consists of stacked, flattened membrane-bound sacs called cisternae. These are arranged in parallel bundles and modify, sort, and package proteins and lipids. Tubules are thin tubes, vacuoles are storage sacs, and lysosomes contain digestive enzymes.

A cell placed in a hypertonic solution will shrink due to water loss. In a hypertonic solution, the external environment has a higher solute concentration than inside the cell, causing water to move out of the cell by osmosis. Isotonic solutions cause no change, hypotonic solutions cause swelling, and 'monotonic' is not a valid term in osmosis.

DNA stands for deoxyribonucleic acid, which is the molecule that carries genetic instructions for the development, functioning, growth, and reproduction of all known organisms. Option B is incorrect because it should be 'deoxy' not 'dioxy'. Option C is missing 'oxy' and option D is missing 'oxy' as well.

Paramecium is a genus of unicellular ciliated protozoan, commonly studied as a representative of the ciliate group.

The shape and size of a cell is directly related to its specific functions. Cells adapt their structure to perform specialized tasks efficiently - like nerve cells being long for signal transmission, or red blood cells being disc-shaped for oxygen transport. Appearance is just a visual characteristic, not the determining factor. Nucleus and location are cell components, not functional determinants.

Bacteria are unicellular organisms, meaning they consist of only one cell. Fungi, plants, and animals are all multicellular organisms made of many cells working together. This is a fundamental classification in biology - organisms can be unicellular (like bacteria and amoeba) or multicellular (like humans and trees).

Chromosomes are made of DNA and proteins (specifically histones). The DNA wraps around histone proteins to form the chromatin structure, which then condenses into chromosomes during cell division. Vitamins and lipids are not structural components of chromosomes. Option D is incorrect because it excludes DNA, which is the genetic material.