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Cell jot notes . 1.16 -1.23. Cell wars . Thousands of years ago, thousands of people died during epidemics of disease. Disease is a condition that interferes with the well being of an organism. Invaders . They interfere with the cell’s normal activities
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Cell jot notes 1.16 -1.23
Cell wars • Thousands of years ago, thousands of people died during epidemics of disease. • Disease is a condition that interferes with the well being of an organism.
Invaders • They interfere with the cell’s normal activities • An invasion is called an infection ( e.g. of invaders include bacteria, harmful fungi or parasitic worms ). Viruses • Viruses are grouped with invaders (they are non – living as they do not include all parts of a cell) • Viruses are just a strand of genetic information covered by a protein coat. • Viruses are not active until the cell is invaded • They invade cells and create more viruses. They are responsible for diseases including cold sores, colds and influenza.
Defenders • Our immune system defends us from invaders by destroying them. • One defense our body uses to defend us is by using white blood cells to attack the invaders. • When invaders are engulfed in the cell the white blood cell’s lysosomes release special chemicals that destroy the invaders. However, this also destroys the white blood cells. • White blood cells attack and kill bacteria, body’s damaged cells (by bacteria or virus) or poisonous chemicals. Anti-bodies • Another way our body protects us is by using anti-bodies. • They are made by a special type of white blood cell. • They are large molecules that trap/lock invading organisms. • Viruses and invading cells have distinctive molecules on their cell membranes(protein coats). In fact, anti-bodies are designed to fit the shape and lock invading cells.
Water movement in plants • Water is an essential part of plants as it helps the plants convert the energy from the sun into chemical energy. From the ground up • Most plants require an efficient water – absorbing system and water transport system. Water Absorption • Most plants get water from soil • The water is absorbed through the tiny root hairs(are tiny extensions on the surface of the cells of a root). • In fact, root hairs increase the surface area of the cell membrane of the root cell(this allows water and dissolved nutrients such as minerals to enter the cell membrane).
Tubes for transport • For photosynthesis to happen water is very essential raw material. • Plants transport water through tubes known as xylem vessels (form when cell walls are left behind as columns die ) to survive. Just like we have tubes called blood vessels to transport blood inside our body.
Moving water around • Some trees are as 100m tall. For water to reach the top is not fully understood. Scientists believe that root pressure , capillarity and transpiration help to reach the top. Root pressure: Root cells pull certain minerals. The water from the soil enters the cells by osmosis. Then, the water being drawn into the root produces a pressure that pushes the water up the xylem vessels. Capillarity : Liquids tend to cling to the sides of narrow tubes. This tendency helps water to move upside the narrow xylem vessels. Transpiration: As water molecules evaporate from plants(leaves) they pull either water molecules up behind them in a long chain from the xylem vessels. The force produced is called transpiration pull.
From the leaves down • Plants also include phloem vessels that act as another transport system. • Phloem vessels move sugars from the leaves to the stems and roots for food and storage. • In fact, they transport nutrients from the roots to the leaves depending on the amount needed. • The difference between xylem vessels and phloem vessels is that phloem vessels consist of living cells.
Examining the leaf • Leaves can be considered as little factories. • Leaves use the energy of sunlight to combine water(from soil) and carbon dioxide(from air) to form sugars and oxygen.
How a plant survives and where it lives 1. Protection: The cuticle = The cuticle is a coating of wax that covers the leaf and stops water from evaporating from the cells below . 2. Protection: The Epidermis= The epidermis in the leaf helps to protect the cells below(these cells cause the cuticle to be waxy). The epidermis does not include chloroplasts so they can’t perform photosynthesis. 3. Photosynthesis: The Palisade= The palisade is a layer under the cuticle and the epidermis(they do most of the work of the leaf). Also, they include many chloroplasts.
Continued …... 4. Transport: The veins = The vein is a combination of xylem and phloem vessels(Xylem carries water from the roots to the leaf. Phloem carries starch and sugar that was made in the leaf to the other plant cells for food and to roots for storage). 5. Gas exchange: Inside the leaf = Under the palisade cells, many leaves have a spongy area with fewer cells and air spaces. 6. Gas exchange : Inside and out= Air spaces in the leaves allow the movement of gases such as oxygen and carbon dioxide(which is used in photosynthesis ). Small openings called stomatas allow these gases to leave through the waxy cuticle. Stomatasare located on the surface of the leaf and are guarded. The guards act like doors . The stomatasreacts depending on the moisture of the leaf.
Fluid movements in animals • For larger and complex animals, specialized cells work together to move fluids. • In animals the circulatory system carries the nutrient –rich fluids to cells in the body. While the excretory system gets rid of the waste. Circulatory system: • The circulatory system brings oxygen and nutrients in contact with almost every cell. • In our bodies no cell is further than 2 cells away from a blood vessel that carries fresh oxygen and nutrients. • Did you know, that our circulatory has 96 km of blood vessels to sustain 60 trillion cells?
Open and closed circulatory system • In an open circulatory system the blood carrying oxygen and nutrients get pumped to the body cavities where it flows around cells. However, the blood gets drawn back when the heart relaxes. • In a closed circulatory system, the blood is always contained within the blood vessels. For the blood to be supplied to the various tissues some of the larger vessels branch into smaller vessels that supply oxygen, nutrient- rich blood is carried and pumped through the arteries. However, the veins return the blood back to the heart.
Humans’ twin pumps • The hearts of mammals and humans is not just a single pump, but 2 parallel pumps that are separated by a wall of muscle(septum). • The right side of the heart retrieves the low – oxygen blood and sends it to the lungs . The left side of the heart takes the fresh nutrient and oxygen blood from the lungs and delivers it to the cells in our body. After body cells remove and absorb the oxygen and nutrients, the blood gets pumped back to the right side of the heart . One way flow: • Valve help to keep the blood flowing in one direction • They are found on both sides of the heart ( 1st set are located between the atria and the ventricles. The 2nd set is located between the ventricles and the atria).
Excretory system • The excretory system is very important as without it cells would die. • Specialized cells work together to remove wastes through the excretory system. • In most animals the excretory system has a second function which is that it helps regulate the body’s water.
Animal digestive system • Unlike plants, animals are unable to make their own food. So, they get their energy from other organisms or from food products that come from other living things. • They use specialized cells in the digestive system to break down the food. • Digestion is a process where our body breaks down food molecules into smaller molecules . • These smaller molecules are used as “fuel” and for growth and repair. • Enzymes help the process of digestion as they speed up the process.
Digestion in a sac • Animals that include simple body plans(such as hydra) have digestive systems with only single opening • These sac-like cavities both take and eliminate the undigested wastes. Digestion along a canal: • More complex animals such as man,digest food through a tube/ canal that includes a separate opening (mouth) along with an exit (anus). • The parts of our digestive system include: the salivary glands, esophagus, stomach, pancreas, liver, gall bladder, small intestine, large intestine and the anus. (in order)
