Ch14 Growth and Developement Flashcards
1
Q
Growth
A
An irreversible increase in the size & dry mass of an organism
2
Q
What is growth brought by?
A
1.Mitotic cell division (increase in number of cells)
2.Cell enlargement: assimilate food substances & synthesize new materials in the cytoplasm (increase in the size of cells)
3
Q
Development
A
An irreversible change in the form of an organism & an increase in its complexity
4
Q
Development
A
An irreversible change in the form of an organism & an increase in its complexity
5
Q
Development is brought by:
A
Differentiation (Specialisation of cells for division of labour)
6
Q
Seed coat
A
Protects the embryo from damage & attack by microorganisms
7
Q
Plumule
A
Develope into stem and roots
8
Q
Radicle
A
Develope into roots
9
Q
Cotyledon
A
- Protect the delicate plumule, because they cover up the plumule before emerging from the soil.
- Provide food for the germination of the seed because they decrease in size while other structures are developing.
- Carry out photosynthesis to provide more food for the development of seedling because they turn green after emerging from the soil.
10
Q
Water
A
- Softens the seed coat and makes the cotyledons swell, break the seed coat so that the radicle can emerge
- Activates the enzymes in the seeds the enzymes catalyse the hydrolysis of insoluble stored food into simpler and soluble food. Used in respiration to release energy and to form structural components of new cells during growth.
11
Q
Process of seed germination
A
- Radicle emerges and grows downwards to form the root
- root hairs develop to increase the surface area for absorbing water & minerals from the soil
- plumule grows upwards to form the shoot
the growth of the shoot lifts the cotyledons up above the soil the cotyledons protect the delicate plumule tip on their way out - the curved shoot beneath the cotyledons straightens,
the cotyledons turn green and carry out photosynthesis for a few days - young leaves develop to make food by photosynthesis the cotyledons fall off
