Pages in this set

Page 1

Preview of page 1

Topic 2 Revision ­ Divide and Develop

Cell division
HAPLOID half the normal number of chromosomes (23)
DIPLOID the normal number of chromosomes (46)


Mitosis Meiosis
Where it happens Most parts of the body Reproductive organs
Number of daughter cells Two identical nuclei Four genetically different cells
Number of chromosomes…

Page 2

Preview of page 2
GERMINATION: Food is stored in seeds for use during germination.
The graph shows how the dry mass of a seedling changed during germination and early growth.








Why does the dry mass of the seedling fall during days 1 to 4?
Because some of the food store is used in respiration…

Page 3

Preview of page 3


Embryonic Stem Cells
Embryos have stem cells which can grow into any type of body cell
Embryos left over from fertility treatment are used
Advantages
1. They have no Hayflick limit
2. Can grow into any cell
3. May be used to replace/repair damaged cells/tissue or grow organs
4. Transplanted…

Page 4

Preview of page 4


Size range of a species
Most plants keep growing for all of their lives, animals stop growing when they reach a certain size.

Factors affecting growth and distribution of plants

PHOTOSYNTHESIS: Carbon dioxide + water glucose + oxygen

Factors that can affect the rate at which plants grow















A B…

Page 5

Preview of page 5
Stomata function Yellow leaves with dark spots
Phosphorous Making roots
Making DNA, RNA, ATP, phospholipids,
Purple leaves, small roots
enzymes, proteins, membranes

To prevent/ resist disease
In photosynthesis and respiration

How mineral ions from the soil are absorbed into root hair cells
1. Mineral ions are dissolved in water in…

Page 6

Preview of page 6

Changes that occur in the stump to allow the leg to regenerate
1. The wound is sealed by a scab
2. A ball of cells which are undifferentiated stem cells (no Hayflick limit) grows by mitosis
3. The cells differentiate
Benefit to humans from research into leg regeneration in newts.…

Page 7

Preview of page 7



How to produce dwarf wheat plants from normal size wheat plants
1. Select the wheat plants with shorter stems
2. Cross breed individual wheat plants with shorter stems
3. Collect seeds and grow offspring
4. Repeat for many generations
Cloning
Plants
Nearly all the bananas we buy today are the…

Page 8

Preview of page 8










































Is it right to clone body parts?
Pros: Could provide tissue/organ transplants to treat human disease
Cons: Many embryos die
Premature ageing/death of clones
Unknown consequences e.g. animal virus transferred to humans (xenovirus)

Ethics Genetic Modification

GENE MODIFICATION: Inserting genes from one organism into another,

Potential benefits of GM organisms:…

Page 9

Preview of page 9
Help reduce food shortages
Bacteria can be used to produce human insulin for people with diabetes
Ready source of product
Pollution free/environmentally friendly
Greater yield
Possibility of disease free livestock

How bacteria are genetically modified to produce human insulin:
· Human genes are removed from DNA using enzymes
· Human…

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »