FreeNotes
The cell wall is a rigid, protective structure surrounding the plasma membrane in plant cells, fungi, and some bacteria. It provides mechanical strength, protection, and regulates water intake. Composition of the Plant Cell Wall The primary cell wall is made of cellulose, providing flexibility and strength. The secondary cell wall (in mature cells) contains lignin, … Read more
The cell membrane is a selectively permeable structure that surrounds the cell, maintaining its integrity while regulating the movement of substances. The most widely accepted model of the cell membrane is the fluid mosaic model, proposed by Singer and Nicolson in 1972. Structural Model of the Cell Membrane (Fluid Mosaic Model) The cell membrane is … Read more
Golgi apparatus (for secretion of digestive enzymes). Rough endoplasmic reticulum (for protein synthesis). Mitochondria (for energy production to support secretion). Related Questions: Why are mitochondria known as the powerhouse of the cell? What makes red blood cells more suitable for the transport of oxygen? Keeping in view the parts labeled 1 to 4 in … Read more
Unripe oranges contain chloroplasts with chlorophyll (green). During ripening, chloroplasts convert into chromoplasts, which contain carotenoids (orange pigments) Related Questions: Why are mitochondria known as the powerhouse of the cell? What makes red blood cells more suitable for the transport of oxygen? Keeping in view the parts labeled 1 to 4 in the plant cell … Read more
Red blood cells (RBCs) in animals lack a nucleus to store more hemoglobin for oxygen transport. Xylem vessels in plants lack nuclei to allow continuous water flow. Related Questions: Why are mitochondria known as the powerhouse of the cell? What makes red blood cells more suitable for the transport of oxygen? Keeping in view the … Read more
Structures present in all cells and their functions: Cell membrane – Controls movement of substances in and out. Nucleus – Stores genetic material (except prokaryotes). Chromosomes – Carry genetic information. Cytoplasm – Site for biochemical reactions. Ribosomes – Protein synthesis. RER & SER – Protein and lipid synthesis. Golgi apparatus – Modifies and packages proteins. … Read more
Components of the fluid mosaic model: The fluid component is phospholipids, which allow movement and flexibility. The mosaic component is proteins, embedded in the membrane for transport and signaling Related Questions: Why are mitochondria known as the powerhouse of the cell? What makes red blood cells more suitable for the transport of oxygen? Keeping in … Read more
1. Red blood cells – Biconcave shape increases surface area for oxygen transport. 2. Nerve cells – Long and branched structure helps in signal transmission. 3. Muscle cells – Elongated and flexible structure allows contraction and movement. Related Questions: Why are mitochondria known as the powerhouse of the cell? What makes red blood cells more … Read more
a. The structure labeled E is the nucleolus, and F is the nuclear membrane. b. The function of F (nuclear membrane) is to protect the nucleus and regulate the movement of materials between the nucleus and cytoplasm. c. The nucleolus (E) forms ribosomes. d. During cell division, the nuclear membrane (F) disappears temporarily to allow … Read more
a. The structure that controls cell activities is nucleus (part 4). part 1 (cell wall) surrounds the plasma membrane of plant cell. b. The biochemical process taking place in part 2 (chloroplast) is photosynthesis. c. If part 4 (nucleus) is removed, the cell will lose its ability to control functions and eventually die. If part … Read more