chapter 1 Flashcards
From what did land plants evolve from? and what do they share?What is it supported by?
Land plants evolved from green algae. Both shared a common ancestor over 1 BYA.
This is supported by DNA sequence data: a fresh water green algae, gave rise to the land plants.
What are land plants and green algae collectively known as?
What is the exception?
green plants
the exception is brown and red algae
The green plants are photoautotrophic(autotrophs), what does this mean?
they obtain their energy from photosynthesis.
Note: Not all photoautotrophs are plants (ex. Some bacteria and protists are photosynthetic.)
What features do plants and algae share?
*Both are photosynthetic and have the same photosynthetic pigments (chlorophyll a+b).
*Both store their excess carbohydrates as starch.
Where do most algae live, and where did they evolve to live?
In the sea. They evolved to live in freshwater environments.
The green algae are divided into 2 groups; What are they? What functions do they have?
a)The chlorophytes, which never made it to land(aquatic/mainly in sea)
b)The charophytes, (group of fresh water algae) which are a sister clade to all the land plants.
What are the charophytes and the land plants referred to?
Streptophytes
Unlike their ancestors, what do charophytes(land plants) have?
-Multicellular haploid and diploid stages in their life cycles.
-a diploid embryo: innovation of the land plants.
To live on lands, plants developed adaptations to overcome what problems?
1-Water loss
2-harmful effects of the sun
3-poor dissemination(spread) of gametes for reproduction.
How did fungi help plants to colonize the land?
They helped to make nutrients available to plants.
What adaptation did plants develop to prevent water loss and protect from desiccation(drying out)?
Development of a waxy and impermeable cover called cuticle on the outer plant surfaces.
Does the cuticle allow gas exchange? Why or why not?
No, the cuticle is impermeable.
What adaptation did plants develop to allow gas exchange?
Development of tiny openings called stomata.
What adaptation did plants develop to move water and nutrients?
Development of a conducting system; vascular tissues.
What effect does the development of a conducting system; vascular tissues have on the plants’ size?
Plants increase in size, they grow tall.
Xylem
conducts water
Phloem
conducts sugars and dissolved nutrients
What are plants with vascular tissues called? What can they do wrt size?
tracheophytes ; they can grow tall
Which plants lack vascular tissues and are always small/restricted in size?
Primitive plants; bryophtes and mosses
Which vascular tissue conducts water?
the xylem
Which vascular tissue conducts sugar and dissolved nutrients?
the phloem
Tracheophytes
plants with vascular tissues; they can grow tall
Primitive plants(Bryophytes/mosses)
plants that lack vascular tissues and are always small/restricted in size
What adaptation did plants develop to mask deleterious recessive mutations caused by exposure to high UV radiation land?
They shift to a dominant diploid generation (stage) in the life cycle.
What happens as a result of plants shifting to a dominant diploid generation in their life cycle?
Larger number of alleles persist in the gene pool, creating greater genetic diversity.
What adaptation did plants develop to protect the embryo from desiccation?
Development of reproductive strategies suitable to life on land.
What are the multicellular sex organs of plants called?
Gametangia
What is the female gametangium that produces a single egg called?
archegonium
What is the male gametangium that produces many sperm called?
antheridium
After fertilization, what happens to the zygote?
the zygote develops into a multicellular embryo within the archegonium.
Gametangia
multicellular sex organs of plants
Archegonium
the female gametangium that produces a single egg
Antheridium
the male gametangium that produces many sperm?
Are plants unicellular or multicellular?
Multicellular
What are the 2 main phases in plants’ life cycle?
They have a multicellular haploid and a multicellular diploid phase in their life cycle.
What does haplodiplontic life cycle mean?
with multicellular (N) haploid and (2N) diploid stages.
What is the haploid generation called?
Gametophyte
What is the diploid generation called?
Sporophyte
What happens during the gametophyte generation?
It starts with (N) haploid spores. Each spore germinates into a gametophyte. At maturity, the gametophyte produces gametangia: Each archegonium produces an egg (N) and each antheridium produces many sperm (N)
In plants, gametes are produced as a result of mitosis.
Egg and sperm unite via fertilization producing a zygote (2N) which is the start of the sporophyte generation.
What happens during the sporophyte generation?
It starts with the diploid zygote. The zygote grows into a multicellular embryo and then into a sporophyte plant. The sporophyte produces at maturity sporangia= cases bearing spore-mother cells or sporocytes (2N). Within sporangia, sporocytes undergo meiosis.
Each sporocyte produces 4 haploid spores.
In plants, spores are produces as a result of meiosis
What type of life cycle do animals and humans have?
They have a diplontic life cycle: only the diploid stage is multicellular( the haploid gametes are unicellular)
In animals, the (N) haploid gametes are produced as a result of what?
Meiosis
After the gametes fuse, what happens?
they produce a (2N) zygote which grows by mitosis to form a multicellular embryo
In animals, what is the only haploid (N) stage/organ?
gamete
What are the seedless non-tracheophytes that reproduce via spores?
Bryophytes(Mosses and liverworts)