Chapter B4: Organising Animals And Plants Flashcards
What is the role of the waxy cuticle?
It is water proof and is a protective layer.
What is the role of the upper epidermis?
It is transparent and one cell thick and has no chloroplasts which allows light to enter the leaf.
What is the role of the chloroplasts?
They trap sunlight energy.
What is the role of the pallisade mesophyll layer?
Tightly packed cells and receives the most light so it contains the most chloroplasts.
What is the role of the spongy mesophyll layer?
There are air spaces for efficient gas exchange. It also gives a large SA/V ration meaning maximum absorption of gases.
What is the guard cell?
They open and close the stoma and contains chloroplasts for photosynthesis.
What is the stoma?
Its like a pore. There are lots of stomata on the lower surface of the leaf.
What is xylem?
It transports water and mineral ions from the roots to the stems and leaves (transpiration).
What is phloem?
It transports dissolved food substances (sugars e.g. glucose) from leaves to the rest of the plant for immediate use or storage (cell sap in vacuole). This movement is known as translocation.
What are communicable diseases?
They are caused by pathogens and can be passed on from one person to another e.g. chicken pox and HIV.
What are non-communicable diseases?
They are not caused by pathogens and can not be passed on from one person to another e.g. most cancers, diabetes, arthritis and mental health conditions.
What is health?
The state of physical and mental well-being.
What is the human defence system?
It protects the body against disease-causing micro-organisms (ie pathogens), bacteria, viruses and fungi.
What does the general defence system do?
It tries to stop pathogens from entering the bloodstream. It is made up of the body’s natural barriers. They act against all pathogens.
What is the specific defence system?
If the general defence system fails, the body relies on the specific defence system. This is made up of white blood cells, found in the blood. The phagocytes engulf the pathogens and the lymphocytes produce antibodies which will kill pathogens.
