Notes 2 Flashcards
What adaptations do Danelions have?
Pappus, fine hairs to reduce the falling velocity of seed and help dispersal on wind currents. Can locate new resources, reduce the possibility of inbreeding, and limit competition
What are seeds made of?
A seed consists of an embryo and nutrients surrounded by a protective coat to keep out drought. When conditions are good, the seed germinates and uses stored food to grow before it has the capacity for photosynthesis.
What else are in seed plants besides seeds?
In addition to seeds, there are reduced gametophytes, heterospory, ovules, and pollen in all seed plants.
Advantages of reduced gametophytes?
-The gametophytes of seed plants develop within the walls of spores that are retained within tissues of parent sporophyte.
-Protects from environmental stressors.
-Provides nutrients
T or F: Non vascular plants have reduced gametophytes
False. In Mosses and other non-vascular plants, are gametophyte dominant and have reduced sporophytes that are dependent on gametophyte for nutrition.
T or F: Seedless vasular plants and seed plants (gymno and angio) have reduced gametophytes.
True. In Ferns and other seedless vascular plants, have reduced gametophytes, that are independent (photosynthetic and free-living), and are sporophyte dominant. In seed plants (gymnosperms and angiosperms), have reduced gametophytes that are dependent on sporophyte tissue for nutrition, and are sporophyte dominant.
Functions of megasporangia?
Megasporangia produce megaspores that give rise to female gametophytes. Each megasporangium has a single functional megaspore.
Functions of microsprorangia?
Microsporangia produce microspores that give rise to male gametophytes. Each microsporangium contains a vast number of microspores
What is in an ovule?
An ovule consists of a megasporangium, a megaspore, and one or more protective integuments. (gymno have 1, angio have 2). Inside each ovule, a female gametophyte develops from a megaspore and produces 1 or more eggs.
A microspore develops into what?
A microspore develops into a pollen grain, that consists of a male gametophyte enclosed within the pollen wall. The tough wall contains sporopollenin that protects it during transportation.
What is pollination?
Pollination is the transfer of pollen to a part of a seed plant containing ovules. Pollen eliminates the need for a film of water and can be dispersed great distances by air or animals. If a pollen grain germinates (begins growing) it gives rise to a pollen tube that discharges sperm into the female gametophyte within the ovule.
How does an ovule turn to a seed in a gymnosperm?
- A fleshy megasporangium is surrounded by a protective layer of tissue called an integument. The micropyle opening allows entry of a pollen grain.
- A megaspore develops into a female gametophyte which produces an egg. The pollen grain that entered through the micropyle contains a male gametophyte. The male gametophyte develops into a pollen tube that discharges sperm, fertilizing the egg.
- Fertilization initiates the transformation of an ovule into a seed which consists of a sporophyte embryo, food supply, and a protective seed coat. Megasporangium dries out and collapses.
T or F: A seed devlops from the whole ovule.
True. A seed develops from the whole ovule. A seed is a sporophyte embryo, along with its food supply, packaged in a protective coat.
What are the benefits of seeds?
Seeds provide some evolutionary benefits over spores like remaining dormant for days to year until conditions are favourable, they have a supply of stored food, and they may be transported long distances by wind or animals.
Gymnosperm means ___?
Gymnosperm means naked seeds. The seeds are exposed on modified leaves (sporophylls) that form cones (strobili).
