Biology

• Unicellular - bacteria, yeast, amoeba.
• multicellular - animals and plants
• Protoplasm - living material of an animal cell.
• protoplasm consists of nucleus, cytoplasm, cell membrane.
• cell membrane-mainly proteins and lipid molecule.
• • function of cell membrane -1. holds the parts of a cell together. 2. controls the passage of substances(water and glucose) in and out(=semi permeable)
• A cell is a basic unit of life
• Cytoplasm is a jellylike substance which consists of 80% water and 20% dissolved substances. Also contains organelles such as mitochondria and ribosome.
• Function of cytoplasm = the site for many chemical reactions.
• Mitochondrion(plu:mitochondria) where aerobic respiration occurs and where energy is released in form of adenosine triphosphate(ATP)
• Adenosine triphosphate is ATP
• Chromosomes contain genes that determine characteristics of an individual
• Ribosomes are sites of protein synthesis
• Lots of mitochondria is muscle cells
• Nucleus contains genetic material (DNA)
• Cell membrane controls what enters or leaves cell
• The nucleus is the largest organelle in the cell
• Nucleus is surrounded by nuclear membrane and contains a nucleolus
• Nucleus contains chromatin made up of coils of DNA bound to proteins
• DNA is deoxyribonucleic acid
• Chromosomes are made of DNA twisted around proteins called histones.
• Nucleus controls all activities taking place in a cell. It is important for cell division.
• The chromosomes determine the characteristics of an organism.
• Cell wall is made up of cellulose and is completely or fully permeable to water, gases and dissolved substances like salt and sugar.
• Cell wall gives shape, support and protection to the cell. It prevents the cell from absorbing too much water and keeps it from bursting.
• Protoplasm of plant cell is the chloroplasts and large central vacuol.
• Chlorophyll absorbs light which is used in photosynthesis. It stores starch which is food for plants and animals.
• Large central vacuole acts as a store of food. It provides turgor pressure to support the cell. It stores waste products to be removed from the cell.
• Magnification is the number of times an image is bigger than the objects.
• Examples of specialized cells are Root hair cell and Xylem vessels.
• How is root hair cell adapted to its function?

  > Being long and narrow, this increases the surface area for absorption of water and mineral salts.

  It is in very close contact with the water film surrounding soil particles.