Science - Grade 8
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Human Organ: Skin
Skin is the largest organ in the human body. It covers and protects everything inside the body, including muscles, bones, and organs. The skin helps keep germs out and prevents the body from losing too much water. The skin has three main layers. The outer layer is called the epidermis. It protects the body from dirt and bacteria. The middle layer is the dermis, which contains sweat glands, nerves, and hair follicles. The deepest layer contains fat that helps keep the body warm. Skin also helps control body temperature. When the body becomes too hot, sweat glands produce sweat. As the sweat evaporates, the body cools down. Tiny nerve endings in the skin allow people to feel heat, cold, pressure, and pain. Another important job of the skin is producing Vitamin D when exposed to sunlight. Healthy skin is important for overall health and protection.
Added: May 10, 2026
Chemical Bonds – MCQs
Chemical bonds are forces that hold atoms together in molecules, allowing the formation of important biological compounds. Covalent bonds share electrons, ionic bonds transfer electrons, and hydrogen bonds form weak attractions between molecules. These bonds are crucial for the structure, stability, and energy of biomolecules, and hydrogen bonding gives water its life-supporting properties.
Added: March 2, 2026
Properties of Water – MCQs
The Amazing Properties of Water: Life’s Essential Molecule Water is more than just a liquid we drink every day—it’s the foundation of life on Earth. Every living organism, from the tiniest bacterium to the largest whale, depends on water’s unique properties. But what makes water so special? Let’s dive into the science behind this remarkable molecule.
Added: March 2, 2026
GENETICS
The scientific study of biological inheritance is called genetics. Gregor Mendel's experiments of cross-pollinating pea plants led to two basic discoveries: first, traits or characteristics are passed from one generation to the next by means of genes, called alleles, exhibit dominance and recessiveness.
Added: February 7, 2026
Mitosis
Mitosis is a vital process that allows living organisms to grow, heal, and replace damaged cells. Every time your body heals a cut or replaces old skin cells, mitosis is happening! Let’s explore how this amazing process works. What Is Mitosis? Mitosis is the process by which one cell divides its nucleus to form two identical daughter cells. Each new cell receives the same genetic information as the original cell. Mitosis is part of the cell cycle and is followed by cytokinesis. The Four Stages of Mitosis: Scientists often remember the stages using the acronym PMAT: 1. Prophase: Chromosomes condense and become visible. The nuclear membrane begins to break down. Spindle fibers start to form 2. Metaphase: Chromosomes line up across the middle (equator) of the cell. Spindle fibers attach to the centromeres of chromosomes. 3. Anaphase: Sister chromatids are pulled apart. Each chromatid moves to opposite sides of the cell. 4. Telophase: Two new nuclei form around the separated chromosomes. Chromosomes begin to uncoil and return to chromatin. Cytokinesis: The Final Step After mitosis, cytokinesis occurs. This is when the cytoplasm divides, forming two separate daughter cells: In animal cells, the cell membrane pinches inward. In plant cells, a cell plate forms between the two new cells. Why Is Mitosis Important? Mitosis is essential for: Growth – from a single cell to a full organism Repair – healing wounds and damaged tissues Replacement – replacing old or dead cells Without mitosis, multicellular life would not be possible. Fun Fact: Some human cells, like skin cells, divide frequently, while others, like nerve cells, rarely divide at al
Added: February 1, 2026
Cell Cycle – Multiple Choice Questions
Every living organism is made of cells, and for life to continue, cells must grow, repair themselves, and reproduce. This process happens through a series of organized steps called the cell cycle. Understanding the cell cycle helps students learn how organisms develop, heal, and stay healthy.
Added: February 1, 2026