For this IBDP Biology blog post, we will be looking at the different conditions needed for seeds to grow, as well as specifically the flowering process for Angiosperms.
Factors for Seed Germenation
Seeds will not germinate unless external conditions are suitable. Factors needed for germination are:
- Availability of water
- Availability of oxygen
- Warmth is needed
To test an hypothesis:
- A control treatment giving the seeds all the factors needed
- A treatment giving the seeds all the factors except one
If the seeds with all the factors are able to germinate and the seeds that are missing one factor do not germinate - concluded that the missing factor is needed for germination
Once seeds are formed they are dehydrated and become dormant. If conditions are favourable the seed will germinate
Water - rehydrate the dried seed tissues Temperature - Enzyme Activity
- Oxygen - allow aerobic respiration to produce ATP
Control Flowering in Angiosperms
- Apical meristem produces more stem and leaves till it recieves a stimulus which makes it change to producing flowers (floral meristem)
- This switch is a change in gene expression in the shoot apex cells
The switch to flowering is in response to a stimulus: the length of light and dark periods (photoperiods) in plants
- Short day plant: Chrystanthemums
- Long day plant: Iris
SIGNIFICANT FACTOR: LENGTH OF NIGHT
Floral Initiation: Caused by the growth and differentiation of apical cells
- Cell in shoot apex change how they divide and differentiate - because of changes in gene expression
- The triggers for change in gene expression vary between plants but the most common is day length
That is all for this post!
References:
- https://www.google.com/url?sa=i&url=http%3A%2F%2Fib.bioninja.com.au%2Fhigher-level%2Ftopic-9-plant-biology%2Funtitled-3%2Fgermination.html&psig=AOvVaw2RuJwgV7yKs1S_5pAXor5D&ust=1627237733913000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCMis7Yyr_PECFQAAAAAdAAAAABAD
Drafted by Venetia (Biology)