Please enable JavaScript.
Coggle requires JavaScript to display documents.
microscopy, gcse biology - Coggle Diagram
-
gcse biology
-
plant organization
The main roles of plant stems and roots are to transport substances around. They have two types of transport systems - xylem and phloem. Xylem transports water and minerals. Phloem transports sugars and amino acids dissolved in water.
These are distributed differently in roots and stems. In the root, the xylem forms a central column. It forms a solid support. The phloem is towards the centre, outside the xylem
In the stem, the transport tissues of the xylem and phloem are grouped into vascular bundles.
-
-
plant transport systems
xylem
-
In a mature flowering plant or tree, most of the cells that make up the xylem are specialised cells called vessels.
vessels
Lose their end walls so the xylem forms a continuous, hollow tube.
Become strengthened by a chemical called lignin. The cells are no longer alive. Lignin gives strength and support to the plant. We call lignified cells wood.
-
phloem
The phloem moves food substances that the plant has produced by photosynthesis to where they are needed for processes such as growth, storage, developent
-
-
-
Sieve tubes - specialised for transport and have no nuclei. Each sieve tube has a perforated end so its cytoplasm connects one cell to the next.
Companion cells - transport of substances in the phloem requires energy. One or more companion cells attached to each sieve tube provide this energy. A sieve tube is completely dependent on its companion cell(s).
transpiration
When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates and diffuses out of the leaf
-
euklaryote
-
-
-
-
cells of plants, animals and fungi are eukaryotic
-
transport in cells
osmosis
The diffusion of water molecules, from a region where the water molecules are in higher concentration, to a region where they are in lower concentration, through a partially permeable membrane.
-
When the concentration of water is the same on both sides of the membrane, the movement of water molecules will be the same in both directions. There will be no net movement of water molecules. In theory, the level of solution two will rise, but this will be opposed by gravity and will be dependent on the width of the container
active transport
Active transport is a process that is required to move molecules against a concentration gradient.The process requires energy.
Substances are transported passively down concentration gradients. Often, substances have to be moved from a low to a high concentration - against a concentration gradient
For plants to take up mineral ions, ions are moved into root hairs, where they are in a higher concentration than in the dilute solutions in the soil. Active transport then occurs across the root so that the plant takes in the ions it needs from the soil around it
In animals, glucose molecules have to be moved across the gut wall into the blood. The glucose molecules in the intestine might be in a higher concentration than in the intestinal cells and blood – for instance, after a sugary meal – but there will be times when glucose concentration in the intestine might be lower.
All the glucose in the gut needs to be absorbed. When the glucose concentration in the intestine is lower than in the intestinal cells, movement of glucose involves active transport. The process requires energy produced by respiration.
diffusion
will end up evenly spread throughout the liquid or gas, but will continue to move
will move in both directions, but there will be a net movement from high to low concentration
bioenergetics
respiration
-
Respiration is only around 40 per cent efficient. As animals respire, heat is also released. In birds and mammals, this heat is distributed around the body by the blood. It keeps these animals warm and helps to keep a constant internal temperature
aerobic
Respiration using oxygen to break down food molecules is called aerobic respiration. Glucose is the molecule normally used for respiration – it is the main respiratory substrate. Glucose is oxidised to release its energy.
anaerobic
Most organisms cannot respire without oxygen but some organisms and tissues can continue to respire if the oxygen runs out. These organisms and tissues use the process of anaerobic respiration.
Human muscle can respire anaerobically for short periods of time – even though the process is relatively inefficient, it's better to continue respiring and be able to run away from danger – or run a race.
photosynthesis
During photosynthesis, plants produce glucose from simple inorganic molecules – carbon dioxide and water – using light energy.
Photosynthesis requires energy in the form of light to drive the chemical reaction. Photosynthesis is an endothermic reaction.
The light energy required is absorbed by a green pigment called chlorophyll in the leaves. Chlorophyll is located in chloroplasts in plant cells, particularly the palisade and spongy mesophyll cells.
The carbon dioxide required for photosynthesis comes from the air. It enters leaves through the stomata. Water enters the plant through the roots, and is transported to the leaves in the xylem.
Oxygen is formed as the waste product. Some is used for the plant's respiration, and also released which makes it available for respiration to animals and many microorganisms. During the day, provided the rate of photosynthesis is sufficiently high, plant leaves, and water plants, give out oxygen.
-
-
coordination and control
The Nervous System
homeostasis
Homeostasis maintains optimal conditions for enzyme action throughout the body, as well as all cell functions.
-
-
-