Year 9 Term 3 Flashcards
What is the usual condition in the stomach
Acidic
What is the usual condition in the small intestine
Alkaline
What is the relationship between temperature and rate of digestion
As the temp increases, so does the rate of digestion until it reaches an optimum temp. Then the enzymes denature and the rate drops
Organs of a plant
Roots
Stem
Leaf
Tissues of a plant
Xylem
Phloem
Epidermal tissue
Mesophyll
What’s the epidermal tissue
It covers the plant
What is mesophyll
Carries out photosynthesis
What is the phloem
Transports dissolved sugars from the leaves (where they are made in photosynthesis) to the rest of the plant for immediate use or storage. The phloem form continuous tubes from the stem to the roots
What is the xylem
Xylem tissue transports water and mineral ions from the roots to the stems and leaves. Composed of hollow tubes strengthened by lignin, adapted for transport of water in the transpiration stream
What is the cambium
Where new xylem and phloem are grown
What is transpiration
The process of water moving up a plant against gravity through the xylem. Water evaporates through the stoma and moves out the leaf. The water is drawn through the xylem like a straw and produces a flow of water
How can transpiration be measured
Can be measured using a potometer which can be used to show how the uptake of water changes in different conditions. It gives you a good idea of how much water the plant loses.
How does temperature affect the rate of transpiration
It increases because by increasing the temp it increases the kinetic energy of molecules which makes diffusion, osmosis and evaporation happen faster
How does humidity affect the rate of transpiration
Decreases because when the air is humid there is more water vapour in it and so is less able to accept more water molecules by evaporation
How does wind affect the rate of transpiration
Increases because the wind blows water vapour away from the stoma keeping the concentration gradient high
How does light intensity affect the rate of transpiration
Increases because light causes the stoma to open. Wider stoma allow faster diffusion of water vapour out of the leaf
How has the leaf adapted to transpiration
The leaf is thin and has a large surface area and has stomata mainly on the lower surface and spongy mesophyll cells
What does the waxy layer do
The waxy layer is a waterproof layer on the upper epidermis. This prevents water loss
What does the spongy do
The spongy layer has rounded cells which are not tightly packed so have a large surface area for gas-exchange
What do the guard cells do
They open and close the stomata to control water loss (also allows gases to move I a mad out)
What do the arrangement of cells do
It means there is a short diffusion distance
What is translocation
The movement of food molecules through the phloem
How are sugars used in respiration
To release energy
How are sugars used in meristems
At the tips of roots and shoots where cells are dividing by mitosis for growth
How are sugars used in cell walls
To make cellulose
How are sugars used in the stems or roots
Stored as starch because starch is insoluble
How is the phloem composed
Composed of tubes of elongated cells. Cell sap can move from one phloem to the next through pores on the end walls
Transpiration
Loss of water vapour though the stomata which are on the underside of a leaf
How does transpiration happen
Water is pulled up through xylem to replace water that has just evaporated. Water comes from transpirational stream and anything that effects the rate of evaporation will effect the rate of transpiration
What is transpiration measured with
Potometer
How has the leaf adapted to transpiration
The leaf is thin and has a large surface area, waxy layer,
Translocation
Movement of food molecules through the phloem
Pathogen
A microorganism which cause disease
4 main groups of pathogens
Bacteria, viruses, fungi, Protozoa
Example of bacteria
Pneumonia
Sore throat
TB
Example of viruses
Common cold
Chicken pox
HIV
Examples of fungi
Thrush
Athletes foot
Example of Protozoa
Dysentery
Malaria
How do bacteria cause disease
Reproduce by splitting into 2, they can cause tissue damage and release harmful toxins. It is our response to the toxins that make us feel ill
How do viruses cause disease
They enter the body and take over the cells and destroy them as they reproduce. Also cause tissue damage and release harmful toxins
Passive immunity
Fist defence against pathogens and aimed at stopping the pathogen getting into the body in the first place
Examples of passive immunity in body
Stick mucus traps pathogens
Enzymes in tears
Skin acts as barrier
Active immunity
Secondary defence and the white blood cells have key function in this
How do WBC’s help to defend against pathogens
Ingesting pathogens (phagocytes)
Produce antibodies which destroy a particular bacteria or virus (lymphocytes)
Produce antitoxins which counteracts the toxins released by pathogens (lymphocytes)
Toxin
Type of natural poison produced by an organism often as a form of protection
Antibody
A protein released by a lymphocyte with a chemical to ‘fit’ to a certain antigen
Antigen
A protein or toxin from the pathogen which then triggers an immune response
How does the immune system work
Every cell has unique proteins called antigens on its surface
Pathogens have antigens that are different than normal ones
Immune system recognises them as foreign
WBC’s (lymphocytes) make antibodies which join with specific antigens
This destroys the pathogens
Memory cells
Some WBC’s remain as memory cells and if they meet the same pathogen a second time they produce more antibodies and destroy them before you feel ill
What is a vaccination
Made up of dead or weakened form of the disease it triggers your natural immune system by stimulating WBC’s to produce antibodies
Pathogen
Micro-organism that causes disease
How does a vaccination work
Small amount of dead or inactive pathogen introduced to body stimulating WBCs
WBCs produce antibodies that destroy pathogen making person immune to future infection
If same pathogen returns body, WBCs produce correct antibodies to destroy preventing infection
