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Diversity of Life B > Week 16 > Flashcards

Week 16 Flashcards

1
Q

What is reproduction in spore plants?

A

reproduction in spore plants (those which reproduce and disperse by spores), leaf epirdemises and seed composition.

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2
Q

What do spore plants consist of?

A

Bryophytes - liverworts, hornworts, mosses
Monilophytes - ferns

Arthrophytes - horsetails
Lycophytes - clubmosses

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3
Q

What are the main differences between a dissecting and compound microscope?

A

Objective lenses - Dissecting microscopes often have a single objective lens, whereas compound microscopes will have usually have 3 objective lenses. This gives dissecting microscopes a smaller range of magnifications.

Magnification - Dissecting microscopes usually have a lower magnification than compound microscopes.

Depth of vision - Dissecting microscopes have two eyepieces giving stereo vision and producing a 3-dimensional image which provides depth. Compound microscopes provide a flat image without depth.

Type of specimen viewed - Dissecting microscopes can be used to view larger specimens, even live organisms, which can be moved around in 3 dimensions easily because there is a greater depth of vision. This may be important for viewing behaviour or the whole body structure of an organism. Compound microscopes usually require specimens to be mounted on slides with a flat preparation because they have a very small depth of vision.

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4
Q

Why are mounted needles used?

A

Mounted needles or pins are used to manipulate and move tissues and structures into the right position.
The very fine point of a mounted needle is good for handling very small structures

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5
Q

What are seekers?

A

Blunt mounted pins, also called seekers, are often used where the structure is delicate and could be pierced or damaged easily.

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6
Q

What are dissecting scissors?

A

Dissecting scissors are used to cut tissues or structures and are easier and safer to use than a scalpel.
Scissors can have straight blades or curved. Curved scissors are often used for small structures or where it is difficult to manoeuvre the larger straight bladed scissors.

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7
Q

Why are forceps used?

A

Forceps are used for moving, holding, or separating structures or tissues. They can be used in conjunction with a scalpel or scissors to safely position the tissue ready for cutting.
Fine forceps have sharp point at the end and can be used for working with very small objects while viewed using a dissecting microscope.

Blunt forceps have a greater surface area and can give a greater grip where more force is needed. They may also be used when the tissues can be damaged by sharp points.

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8
Q

What is the stomata?

A

Stomata are important structures on the aerial surfaces of higher plants. They are microscopic pores usually surrounded by two guard cells. These guard cells are able to regulate the opening and closing of the pores to allow for gas exchange and evapotranspiration.

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9
Q

What are spermatophytes?

A

Plants that reproduce via seeds (instead of spores) belong to the spermatophytes; this group contains the gymnosperms and the angiosperms.

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10
Q

What can the angiosperm be divided in to?

A

he angiosperms can be divided into two main groups, the monocotyledons (monocots) and dicotyledons (dicots). You will be dissecting both a monocot seed (maize) and a dicot seed (bean).

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11
Q

Of the following plant groups, which group is non-vascular?

A

Bryophytes (the mosses) do not have a vascular system with xylem and phloem.

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12
Q

When would you use a dissecting microscope to view a specimen rather than a compound microscope?

A

A dissecting microscope is usually used to view larger specimens in three dimensions because they have a greater depth of field and two stereoscopic eye-pieces.

It is also possible to view live specimens more easily with a dissecting microscope.

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13
Q

You will also be having a close look at mosses, and their reproductive process. Tick all of the following that are features of mosses.

A

Spores

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14
Q

Which of the following do not produce spores?

A

Gametophytes are the male and female gametes.

Arthrophytes include the Horsetails, Lycophytes include the club mosses, and Monilophytes include the ferns, all of which produce spores.

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15
Q

Which of the following groups belong to the spermatophytes?

A

The spermatophytes are seed producing plants, made up of the angiosperms and the gymnosperms. The angiosperms contain the dicotyledons and monocotyledons groups. The other groups listed (arthrophytes, monilophytes and bryophytes) are plant groups that reproduce via spore production, not seeds.

Gymnosperms
Angiosperms
Dicotyledons

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16
Q

Approximately how long ago did green algae and the land plants share a common ancestor?

A

1 billion years ago

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17
Q

The adaptation of plants to a terrestrial environment required _______.

A

better water loss management

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18
Q

Organisms that exhibit a haplodiplontic life cycle have ______.

A

multicellular haploid and diploid stages

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19
Q

In this plant life cycle, the ____ generation is represented by position A, while the ____ generation is at position B.

A

Blank 1: gametophyte or haploid

Blank 2: sporophyte or diploid

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20
Q

In humans, gametes such as sperm and eggs are formed by the cellular process of _____, whereas land plants produce gametes by the process of ____

A

Blank 1: meiosis

Blank 2: mitosis

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21
Q

Approximately 1 billion years ago, land plants shared a common ancestor with ______.

A

green algae

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22
Q

In plants, the haploid generation is called the _____, and the diploid generation is the _____.

A

Blank 1: gametophyte

Blank 2: sporophyte

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23
Q

Choose all features that confined the green algal ancestors of plants to water.

A

Less water availability in a terrestrial environment

Higher levels of UV light on land

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24
Q

In plants, meiosis produces haploid ______.

A

spores

25
Q

A typical land plant has a(n) ______life cycle, which includes multicellular haploid and diploid stages.

A

haplodiplontic

26
Q

In plants, meiosis occurs within what structure?

A

Sporangia

27
Q

Which of the following are involved in haploid gamete production in land plants?

A

Gametophyte

Mitosis

In land plants, meiosis results in the production of spores, not gametes! Gametes divide mitotically to produce the gametophyte. The gametophyte produces gametes by mitosis.

28
Q

Which of the following is true of gamete production in humans and land plants?

A

Gametes are formed by mitosis in land plants.

Gametes are formed by meiosis in humans.

29
Q

In plants, the gametophyte produces _____

and the sporophyte produces ______

A

Blank 1: gametes

Blank 2: spores

30
Q

In plants, spore mother cells undergo ______.

A

meiosis to produce haploid spores

31
Q

In plants, spores are produced within sporangia through the process of

A

meiosis

32
Q

What structure allows hornwort sporophytes to regulate gas exchange?

A

Stomata

33
Q

The main role of plant gametophytes is to produce ______.

A

haploid gametes

34
Q

What clade arose approximately 410 million years ago?

A

Tracheophytes

35
Q

In humans, gametes such as sperm and eggs are formed by the cellular process of _____whereas land plants produce gametes by the process of _____

A

Blank 1: meiosis

Blank 2: mitosis

36
Q

Cooksonia is of interest to plant biologists because it is ______.

A

the first known vascular plant

37
Q

Stomata are typically absent in bryophytes except in ______.

A

hornwort sporophytes

38
Q

Plants that produce one spore type are called ______

A

homosporous

39
Q

Tracheophytes first arose approximately how many years ago?

A

410 million

40
Q

Evidence suggests that leaves evolved more than once; _______are small leaves found in the lycophytes and _____
are the true leaves of ferns and seed plants.

A

Blank 1: lycophylls

Blank 2: euphylls

41
Q

The first known vascular land plant was ______.

A

Cooksonia

42
Q

Scientific evidence suggests that leaves evolved at least how many times?

A

Twice

43
Q

A plant is said to be ____

if all of its spores are similar in appearance.

A

homosporous.

44
Q

Select all types of leaves found in vascular plants.

A

Euphylls

Lycophylls

45
Q

Euphylls likely evolved when ______.

A

branching stems became webbed with photosynthetic tissue

46
Q

What is Symbiosis?

A

Mutualistic or commensal relationships between plants and other organisms.
Nutrition, Disease prevention, pollination, seed dispersal and habitat.

47
Q

Why do the plants become more advanced?

A

They get progressively more advanced as we move to the right and they have evolved different adaptations to coping on land.

48
Q

what was earth like before plants?

A

These pictures represent what Earth might have looked like . The landscape was largely barren with just bare rock exposed. There might have been thin coatings of cyanobacteria and protists, but these would have been the only organisms around. Once plants colonise the land, they enable other life forms to survive, providing food and habitat and are necessary elements to supporting a diverse ecosystem. As these plants started to colonise the land, the landscape will have changed and there may have been a few bryophytes like plants coating the landmasses near the water.

49
Q

What are the properties of Both Chara and Coleochaete?

A

A key fundamental difference to these sister genera are that they-
Both Chara and Coleochaete have haplontic life cycles; whereas all land plants have haplo-diplontic life cycles.

Closest relatives to land plants exist in the charophytes clade. These are considered to be kind of sister-generated to all land plants. We can provide some clues to the ancestry of all land plants. The pictures show Chara and Coleochaete and there are a lot of features about these two genera that led scientists to believe that they were the most closely related groups to land plants. They both have apical meristems, which is where new cells come from, and new tissues are grown. Groups also share a lot of similarities to land plants that suggests that they are the closest relatives and the molecular evidence supports this. Coleochaete is actually a really tiny organism, whereas Chara is a lot more normal.

50
Q

A typical animal life-cycle is

A

A typical animal life-cycle is diplomatic and this would expect you to be very familiar with. What this is telling you is the passing of genetic information from one generation to the next. Most of the time the animal lives as a diploid multicellular being just as you or I. Then in order to continue the life cycle that is starting next-generation gametes are produced by meiosis and come together to form the zygote and fertilisation. This zygote then divides by mitosis, not meiosis, and mitosis keeps the same number of chromosomes through each cellular division to create a multicellular being. Thus maintaining the diploid nature of these cells. The process of meiosis and fertilisation takes us from a diploid cell to a haploid cell and then when two haploid cells come together through fertilisation, it brings us back to a diploid cell.

51
Q

What is the lifecycle of the Chara and Coleochaete?

A

This lifecycle is essentially the opposite in that they spend most of their lives with a haploid state of being. They have multicellular bodies and structures that exist in the haploid stage. That just means that fertilisation and meiosis happen at different points in the life cycle compared to that of an animal life cycle. This time in order to produce gametes, Chara and coleochaete don’t need to undergo meiosis because they’re already haploid. They can just produce different types of cells which have one set of chromosomes in them. When these are joined by fertilisation, we get the formation of the zygote. But unlike with animals, instead of them undergoing mitosis. They actually divide straightaway by meiosis, then produce spores which can then germinate into a new multicellular being. The differences if you look at the cholera as a plant, what you’ll see is haploid cells.

52
Q

Plants evolved many innovations to successfully colonise land

What is one of these?

A

Haplodiplontic life cycle was one of these…

53
Q

Why does greater exposure to UV effect land plants?

A

More likely to have damage to DNA, harmful Greater exposure to UV mutations

54
Q

Why does the need for structural support provide a challenge for land plants?

A

Aquatic plants have water pressure to support them. As the air is less dense you dont have that same pressure and the plant may fall over. Important problem which in the early evolved clades of land plants really limited that growth and how tall they were able to get.

55
Q

Why is water availability a challenge for land plants?

A

As soon as you start to colonise the land, rather than living in water, you suddenly have to worry about where the next drink is coming from. Not only do you need to ensure that you are tapped into a water supply so that you can exist and water is incredibly important for most life, but especially plants. But you also need to prevent yourself from actually losing that water as soon as you find it. Having different innovations that enable you to preserve the water that you’ve absorbed from your surroundings is really integral to the evolution of land plants. But its also necessary for fertilisation. So you need a water medium for your sperm swimming to reach the egg.

56
Q

Why are haploid cycles more likely to suffer from UV?

A

As if you just had a haploid cell then every allele will be expressed because you don’t have choice of two.

57
Q

Why may variation occur in the diploid stage after UV exposure?

A

• Greater chance of generating variation (double the amount of DNA) simply because you’ve got double the amount of DNA present in yourselves. As UV light will act on that DNA and will lead to mutations. You’ve got a better chance of actually generating that variation in the first place, as well as actually masking this whole mutation. This is really great for natural selection because a fundamental principle of NS is providing variation upon which NS can act.

58
Q

What happens as land plants evolve?

A

As land plants evolve, a more dominant sporophyte generation is favoured. Indeed, we see this happen as new species and taxa evolve.
But all of these living land plants have both of these stages still, even the most advanced flowering plants.

Diversity of Life B (11 decks)

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