SB2b-d Flashcards
(15 cards)
What is differentiation?
The process that changes less specialised cells into more specialised ones.
What is a meristem?
A group of cells near the end of each shoot and root that allows plants to continue growing throughout their lives.
How are specialised cells formed in plants?
The cells in meristems divide rapidly by mitosis. Many of the cells produced then elongate and differentiate into specialised cells with different functions.
Name 2 examples of specialised plant cells.
- Root hair cells
- Xylem cells
What does the structure of a plant’s root consist of? (7)
- Root vein (including xylem)
- Packing tissue
- Root hair
- Root cap
- Zone of differentiation
- Zone of elongation
- Zone of cell division (meristem)
Check Biology page 34.
How is growth in plants calculated?
Final value - starting value
___________________________ x100%
starting value
What is a xylem vessel?
A long tube formed from many dead xylem cells.
What are the characteristics and adaptations of a xylem vessel?
- Thickened wall to withstand water pressure
- Tiny pores in wall allow water and mineral salts to enter and leave the vessel
- No cytoplasm, vessel is empty
- Loss of cell walls of two xylem cells to form a tube
What are stem cells?
Cells that can divide repeatedly over a long period of time to produce cells that then differentiate.
Where are stem cells found in plants?
Meristems (also called meristem cells).
What are embryonic stem cells?
The cells of an early-stage embryo that can produce any type of specialised cell.
Describe the development of animals.
Start off as a fertilised egg cell which divides to form an embryo. As cells continue to divide, the embryo starts to develop different areas that will become the different organs. The stem cells in these areas become more limited in the specialised cells they can produce.
What are adult stem cells?
Stem cells that can only produce the type of specialised cell that is in the tissue around them. In human tissues, they allow the tissues to grow and to replace old or damaged cells.
How can stem cells treat different diseases cause by damaged cells?
Stimulating stem cells to make them produce the specialised cells that are needed and then injecting them into the places they are needed.
State 2 problems that could occur with injecting stem cells to treat diseases?
- If the stem cell continue to divide inside the body after they have replaced damaged cells, they can cause cancer.
- The stem cells are often killed by the immune system of other people that they are put into. This is called rejection.
