lec 4 Flashcards
seeds can be split into the purposes of protection, energy, and the new plant. which parts correspond to these roles?
protection: seed coat
energy: cotyledons, endosperm
new plant: embryo - epicotyl, radicle, hypocotyl
if i were to only look at the seed of a plant, how could i tell if it were a monocot?
- one cotyledon
- presence of endosperm
what are the roles of the epicotyl, radicle, and hypocotyl?
epicotyl: becomes shoot
radicle: becomes root
hypocotyl: becomes the connector bw root and shoot
define albuminous + exalbuminous
albuminous: has an endosperm
exalbuminous: doesnt have endosperm
monocots are album while dicots are exalbum
list five pollinating agents
insects, mammals, birds, wind, water
what is the diff bw self and cross pollination?
self is the pollination from one plant’s pollen to its own flower, cross is bw two diff plants
self leads to same genome while cross leads to genetic diversity
bonus: it seems there’s a trend in staple crops, such as wheat, barley, oats, rice, peas, and tomatoes. what is this trend?
self pollinators! under ideal conditions, they spread very quickly
what is dormancy? why may a plant go dormant?
dormancy is when a seed does not germinate, potentially due to bad conditions
may not germinate due to
- impenetrable seed coat
- germination inhibitors
- immature seed embryo
- impermeability of water or oxygen
seeds can go dormant. do farmers like this? are there any repercussions to the actions that farmers may have taken?
no farmers do not like seeds going dormant bc they want crops to grow at the same time
–> sel for plants w seeds that don’t go dormant
problem: now seeds are just germinating whenever they damn feel
–> keep seeds dry, bc when they’re exposed to moisture they germinate
what is the oldest seed that turned to a viable plant?
Silene stenophylla, found in a squirrel burrow under permafrost
what are seed banks? what’s the big seed bank we talked about in class?
stores of seeds, such that seed diversity is preserved in case anything happens?
svalbard international seed vault in norway has over a million seeds
seed strategies incl big and small seeds. why may a plant be advantaged to have a big or small seed?
small seeds: doesn’t req a lot of energy to prod one, so many can be produced. surely at least one will survive and reprod (ex orchids)
big seeds: invest all energy into one seed that is sure to grow and reprod (ex double coconut)
seeds can go dormant, but only for so long. why can they not survive forever?
energy storage is limited, disease may afflict the seed, may get eaten by animals
within a plant’s lifecycle, at what point is it n? when is it 2n?
n when pollen and ovule, 2n at all other times
