Topic 1 Cells

• The cell membrane is selectively permeable, allowing some substances to pass through while preventing others from entering or leaving the cell.
• Organ system: a collection of different organs working together to perform a particular function.
• Organ: Several tissues working together to produce a particular function.
• Tissue: Many similar cells working together and performing the same function.
• Examples of Specialized Cells include Egg cells which carry genetic information for reproduction.
• Tail moves with a whip-like action, allowing sperm to swim.
• Cells in larger organisms cannot survive on their own, for example, heart cells.
• Some microscopic organisms are made of one cell, such as amoeba, which can carry out all the processes needed to keep them alive.
• Egg cells have an adaptation of having a large amount of cytoplasm, containing yolk droplets made up of fats and protein.
• Anton von Leeuwenhoek was the first person to observe protozoan (single cell organism) and spermatozoan.
• Robert Hooke discovered a thin slice of bark of a tree, which closely resembled the structure of a honeycomb or prison, leading to the term “Cell”.
• A cell is the basic structural and functional unit of all living cells.
• Living cells can be divided into Eukaryotic cell and Prokaryotic cell.
• Sperm cells function to carry genetic information for reproduction to fertilize an egg cell, and their adaptation is to have an acrosome that secretes enzymes to digest the cells around an egg and the membrane and a mid-piece packed with mitochondria to provide energy for movement.
• Red blood cells function to transport oxygen around the body, and their adaptation is to have a biconcave shape to increase surface area to enable faster rate of diffusion of oxygen into haemoglobin and to be elastic to allow RBC to squeeze through smaller capillaries.
• Ciliated cells are found in the lining of nose and windpipe, and their tiny cytoplasmic 'hairs' is called cilia.
• Palisade mesophyll cells function to make food for the plant by photosynthesis using carbon dioxide, water and light energy, and they are columnar (quite long) to fit in more chloroplast to trap light energy and their cell wall is quite thin to allow more light to pass through it.
• Nerve cells function to conduct electrical impulses along the fibre, to and from the brain and spinal cord, and their adaptation is to have long axons to allow the impulses to travel a long way before passing it to the next cell and have myelin sheath to provide insulation to allow a faster impulses to be transmitted.
• Examples of Specialized Cells include Ciliated cell, Root Hair Cell, and Palisade Mesophyll Cell.
• Root Hair Cells function to absorb water and mineral salts from the soil, and their adaptation is to have a thin cell wall to reduce diffusion distance and hair-like projections that penetrate between soil particles and offer a large absorbing surface.
• Organisms are individuals animal or plants, formed by all the organs and systems working together to produce an independent living things.
• The adaptation of red blood cells is that they have a biconcave shape, increasing the surface area to volume ratio to facilitate oxygen absorption.
• The function of root cells is to absorb water and mineral salt from soil into roots.
• The function of heart cells is to carry oxygen all around the body.
• The function of xylem cells is to conduct water and ions from the roots to the stem, leaves, flowers and fruits, providing support for the aerial parts of the plants.
• Organs are structures made up of a group of tissues working together to perform a specific function.
• The function of epithelial tissue is to provide a barrier against the environment.
• The adaptation of heart cells is that they have no nucleus, can fit in more haemoglobin, and can carry more oxygen.
• The adaptation of xylem cells is that they are narrow tubes to prevent water column from breaking and assist with capillary action.
• The adaptation of blood cells is that they are small and many, have a very large surface area to facilitate oxygen absorption.
• Organ systems are groups of organs with related functions working together to perform a body function.
• The adaptation of epithelial tissue is that it is long and narrow, increasing the surface area to volume ratio to increase the rate of water and mineral salt absorption.
• Muscle cells cannot get their own food and oxygen.
• Magnification is the observed size of an image divided by the action size of the specimen.
• The adaptation of root cells is that they are long and narrow, increasing the surface area to volume ratio to increase the rate of water and mineral salt absorption.
• Tissue is a group of cells with similar structures working together to perform a shared function.
• Ribosomes can only be seen under electron microscope and are attached to the Endoplasmic reticulum or lie freely in the cytoplasm.
• The nucleus contains dense material called nucleoplasm.
• The cytoplasm is jelly-like with particles and organelles in it and is enclosed by the cell membrane.
• The cytoplasm functions as the site of chemical reactions and contains specialized structures called “organelles”.