What is binary fission explain the process
Binary fission is the process by which bacteria replicate
- circular strands of DNA and plasmids replicate
- DNA strands move to opposite ends of the cell (opposite poles)
- Cytoplasm begins to divide and a new cell wal begins to form
- Cytoplasm divides and 2 new daughter cells are formed. Each daughter cell has one copy of DNA but can vary in the number of copies of plasmids
What is a nucliatide
It is a complete unit of phosphate sugar and base pair
Describe the function of receptors in the skin
Detect and respond to stimulus converting this stimulus into an impulse which is sent to the brain
What 3 things increase the rate of diffusiin
(The concentration gradient)
- this is the difference in concentration of particles between the inside of the cell and outside of the cell. The bigger the visible difference between the amount of molecules inside and outside the cell the faster the rate of diffusion will be
(The temperature)
- higher the temp the faster the rate of diffusion due to the particles having more energy so they move around faster
(The surface area)
- the larger the surface area the more area particles have to pass through at one given time
What is active transport
Active transport is the movement of particles against a concentration gradient from an area of lower concentration to an area of higher concentration USING ENERGY TRANSFERED DURING during RESPIRATION
It can be used to move substances in and out of cells
What is a solute
A solute is a dissolved substance
How are alveoli adapted for gas exchange
- An enourmous surface area 75m2 in humans so they are able to diffuse a lot of oxeygen at one time
- They have thin walls so the diffusion distance is short
- The lining of the alveoli are moist so the gases are able to dissolve easier
- They have a good blood supply as the capillaries are close by so there is a steep concentration gradient
Describe how leaf adaptions have made it more efficient for gas exchange
- Flattened shape of the leaves increases the surfaces area for diffusion in and out of the leaves
- The cell walls inside the leaves have air space in between them which increase the surface area giving more chance for carbon dioxide to get into the cells
What are Guard cells and what are there function
Guard cells are cells which surround the stomato (2 either side)
If the plant is losing water through its leaves faster than the water absorbed through the roots the guard cells close to stop the plant losing more water.
How do lamelle increase the efficiency of gas exchange across the gills
They increase the surface area of the gills available for diffusion of gases therefore the rate of diffusion is increased
How does the direction of the blood flow in the lamella increase the efficiency of gas exchange across the gills
The direction of the blood flow helps maintain a large concentration gradient of oxeygen between the water and the blood because it flows in the opposite direction. The concentration of oxeygen is always higher in the water than in the blood so the net movement of oxygen will be into the blood so as much oxygen as possible diffuses into the blood.
What is an effector and what are the 2 different types of effector and there responses
An effector is a muscle or a Gland that produces a specific response to a stimulus
Muscle - Contract to produce movement
Gland - Secrete enzymes and hormones
Describe the reflex arc in detail
Stimulus is detected by a receptor
Electrical impulse pass from the receptor along a sensory neurone to the Central Nervous System (CNS)
A Chemical is released and diffuses across the synapse to a relay neurone
Relay neurone sends the electrical impulse to the motor neurone
The electric impulse passes down the motor neurone to an effector and a response is produced
List all the main organs contained within the digestive system
Mouth/teeth - entrance to where food goes in and is broken down by chewing
Tounge - move food around to aid chewing
Salivary glands - produce digestive juices (Amalayse enzymes for digestion in the mouth)
Oesaphagus - leads down into the stomach (peristatas is the muscle contracting in a wave like motion to move food down)
Liver - Produces Bile which emulsifies fats and neutralises stomach acid
Gall Bladder - stores bile
Stomach - where food is digested and produces protease, HCl and pummels food with muscular walls
Small intestine - produces protease and lipase, food is absorbed into blood glucose, ions. It large surface area given by villi
Food traces along the apendix to the Large Intestine
Large Intestine - Re absorbtion takes place and indigestible food is passed to. Any excess water is absorbed before it is excreted from the anus
Explain the purpose of the lungs
The purpose of the lungs is to perform gas exchange. Oxygen from the air is needed for respiration. Carbon dioxide also needs to be remevod from the blood.
What is the thorax and the main structures of it
The thorax is the the top part of your body and is separated from the lower half by the diaphragm.
The lungs are protected by the rib cage and surrounded by the pleural membrane.
Air is breathed in and travels down the trachea (windpipe) to two tubes called bronchi.
The bronchi then separate into smaller tubes called bronchioles which end at small bags called alveoli where gas exchange takes place.
Why are the alveoli surrounded by lots of capillaries
Because this is where gas exchange takes place. Oxygen from the alveoli diffuses out into the blood cells in the capillaries and carbon dioxide in the blood cells diffuses into the alveoli
What is a pacemaker
A pacemaker is mechanical device used to control the heart beat of a natural heart. It is placed under the skin and has a wire leading to the heart which sends electronic impulses to the heart causing the heart to beat regularly as opposed to having an irregular beat.
Describe the structure of the arteries
Blood vessels which carry blood away from the heart toward the the organs in the body.
- They branch into capillaries
- Walls are thick and muscular with elastic fibres which allow them to withstand the high pressures at which blood is pumped through them.
- Thick walls compared to there lumen
Describe the structure of the capillaries
- Thin walls to allow for the exchange of substances carrying oxeygen to cells and taking away waste materials e.g. C02
- One cell thick creating a short diffusion pathway
- Large surface area compared to there volume
- Very small Lumen
- close to every cell
Describe the function of white blood cells
- Defend against microorganisms
- Engulf microorganisms and digest them (Phagtotosis)
- Produce antibodies to identify antigens and destroy them
- Produce antitoxins to neutralise toxins produced by certain pathogens
- They have a nucleus
Describe the role which plasma plays in the body
- It is a liquid substance which carries virtually everything in the blood
- Carries soluble products of digestion e.g. glucose amino acids
- Carbon dioxide from organs to the lungs
- Urea from the liver to the kidneys
- Antibodies and antitoxins
Name all the tissues that together form the organs in a plant
- Epidermal tissue a waxy cuticle which covers the whole of the outside of the plant
Pallasade mesophyll tissues this is the part of the leaf where photosynthesis happens located at the top of the leaf where it can get the most sunlight and contains lots of chloroplasts - Spongey mesophyll tissue found in the leaf and contains large air spaces for gas exchange
- Xylem and Phloem tissue carry water minerals and ions around the plant
- Merristem tissue can differentiate into different types of plant cells and is found at the growing tips of shoots and roots
How are the tissues of leaves adapted for Gas Exchange THINK OF WHERE GAS EXCHANGE HAPPENS IN LEAVES AND DESCRIBE
Gas exchange happens in the spongy mesophyll tissue of the leaves. Tiny holes called stomato are located on the underside of the leaves and allow carbon dioxide to diffuse in and oxygen and water vapour to diffuse out.
Air spaces in the spongy mesophyll increase the rate of diffusion as they allow more gases to diffuse in and out the leaves at one time
-
Cell Structure Topic 1a39
-
Topic 1b Transport In Cells40
-
Topic 2a Tissues, Organs And Organ Systems49
-
Topic 2b Health & Disease52
-
Topic 3 Infection and Response50
-
Mixed Questions Hard28
-
Topic 4 Bioenergetics53
-
Topic 5a The nervous system43
-
Topic 5b The Endocrine system31
-
Topic 5c Animal and Plant Hormones33
-
Topic 6a DNA & Reproduction36
-
Topic 6b Genetics23
-
Topic 6c Evolution and classification62
-
Topic 7a Organisms and Their Environment35
-
Topic 7B Human impact on the environment23
