Bio Warm-Up May 2
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What is the tissue difference between seeds of gymnosperms and seeds of angiosperms?
Angiosperms develop a highly nutritious tissue, called endosperm
What is endosperm?
A highly nutritious tissue
When does endosperm originate?
At the same time that an egg is fertilized
In what angiosperms is the endosperm still present in mature seeds?
Corn and wheat
In what angiosperms is the endosperm completely transferred inot the embryo by the time a seed is mature?
Beans and peas
Where are the food reserves stored in some angiosperms?
What are cotyledons?
"seed leaves" similar to the endosperm, provides nutrients for embryo
What are the two classes of angiosperms based on thier number of cotyledons?
- Seeds with two cotyledons called dicotyleons (dicots)
- Seeds with a single cotyledon called monocotyledons (monocots)
What evolved first out of monocots and dicots?
What are the three characteristics of dicots?
- Two cotyledons
- Flower parts in multiples of four and five
- Veins usually netlike
What are the three characterisitcs of monocots?
- One cotyledon
- Flower parts in mulitples of three
- Veins usually parallel
How many sperm are in each pollen grain?
What happens to sperm in most gymnosperms?
One of them dies
What happens with sperm in angiosperms?
Both sperm fuse with certain cells of the megagametophyte
What two cells do sperm of angiosperms fuse with?
- An egg to form the zygote
- Two haploid cells forming a triploid cell that turns into endosperm
What is double feritlization?
The process by which two sperm fuse with cells of the megagametophyte to produce both a zygote and endosperm
Among angiosperms, how did fruits evolve?
More efficient dispersal of seeds
What does a fruit consist?
A mature ovary that contains one or more seeds and often includes other flower parts
What are two characterisitcs of mature seeds?
Often resistant to chewing and digestion
Why are mature seeds not digestible and resistant to chewing?
So they can pass through an animal and be spread out from the parent plant
What are three ways seeds are speciealized to getting transported?
- Sticking to animal's fur
- Floating on wind currents
- Floating on water
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