B5 Flashcards
(33 cards)
What is the name given to a cell that does a particular job?
A specialised cell
What is a group of specialised cells called?
A tissue
What is a group of tissues cells called?
An organ
All cells in an embryo are identical (embryonic stem cells) up to and including what stage?
The eight cell stage
Some cells unspecialised after eight-cell stage and can become specialised at a later stage. What is the name of these cells and how are they different to embryonic stem cells?
They are adult stem cells and they can become many but not all types of cells (they are partly specialised)
In plants, what name is given to the region of cells that are mitotically active ( can divide)?
Meristems
Describe the new cells produce from plant meristem
They are unspecialised plant cells that can develop into any kind of cell.
Identify two types of plant tissue can be formed from unspecialised plant cells.
Xylem and phloem
Identify 4 plant organs
Flowers, leaves, stem and roots
The presence of meristems allows the production of clones from a plant from cuttings. Why would a plant be cloned in a way?
To reproduce a desirable features of the plant.
Describe how to grow a plant from a cutting
A cut stem from the plant must be placed in compost in the presence of plant hormone( auxins). The plant will then grow roots and become a plant of the parent plant.
The growth and development of a plant is affected by the environment. When a plant is affected by light, what is this called?
Phototrophism
Why does phototropism increase the chances of plant survival?
It means the plant gets more light which increases the rate of photosynthesis which leads to growth of the plant
Explain phototropism
Auxins are plant hormones that make some parts of a plant stem grow faster than others.The results is that the plant the plant stem bends towards the light.It does this because light coming from one side destroys the auxins made is this part of the stem.So growth on that side slows down.On the shaded side of the stem there is more auxin.So growth on this side speeds up. The result is that the shoots and leaves are turned towards the light for photosynthesis
Cell division by mitosis produces what?
Two new cells that are genetically identical to each other and the parent cell.
Identify the two main stages of the cell cycle?
Cell growth and mitosis
Explain what happens during cell growth
- The number of organelles in the plant increase
- The chromosomes are copied when the two strands of each DNA molecules seperate and new strands from alongside them .
Explain what happens during mitosis.
- The copies of chromosomes seperate
- The nucleus divides
Meioses is a type of cell division that produce what?
Gametes
Why is it important that in meiosis, the cells produced only contain half the chromosomes number of the parent cell?
Because the cell produced must be able to form a zygote with anther gamete that has a set chromosome from the other parent (23 pairs in total)
What does a zygote contain ?
A set of chromosomes fro each parent
Identify the structure of DNA?
A double helix
What does the order of bases in a gene represent?
The genetic code for the production of a particular protein.
Explain why proteins are made as a result of genes?
The order of bases in the gene is code foe building up amino acids.
Amino acids in the correct order will make the correct protein.
