#guard cells

[tenth-sentence]

Other specialized epidermal cells, such as lithocysts, bulliform cells, silica cells, and cork cells (Figure 19.9), are found only in certain groups of plants and are not studied as well.

"Plant Physiology and Development" int'l 6e - Taiz, L., Zeiger, E., Møller, I.M., Murphy, A.

[biostudyblog]

PLANT FACTS! Part 1

This is me retyping the notes I took on plants + photos of diagrams I drew, so I’m sorry for the quality.

Disclaimer: These diagrams are not my own. I drew diagrams provided in the “Barron’s SAT Subject Test Biology E/M” book, as drawing them helped me memorise and visualise what I was learning. It’s a great book, huge amount of information that I think they did a wonderful job condensing.

Plants are:

multicellular

eukaryotic

photosynthetic/authtrophs

organisms with cell walls made of cellulose

organisms that store carbohydrates as starch (as opposed to animals that store them as glycogen)

Some types of plants are:

Byrophates:

These are plants like moss, liverworts, and hornworts.

They are primitive. They do not have vascular tissue

Because of this lack of vascular tissue, they live in moist environments. Without roots or xylem, they use osmosis to collect water.

They are small, as they lack lignin fortified tissue that allows other plants to grow.

Tracheophytes:

Include ancient seedless plants (like ferns) without seeds, they reproduce using spores.

They have transport vessels like xylem and phloem.

They also include plants with seeds. There are two kinds: gymnosperms and angiosperms.

Gymnosperms:

These plants are conifers (cone bearing plants)

They have distinguishable needle shaped leaves

They also have a thick waxy cuticle, and stomates in stomatal crypts.

They include: sequoias, redwoods, pines, yews, and junipers.

Angiosperms:

Instead of seeds on the surface of cones, these plants have flowers with ovaries that contain their seeds.

Include roses, daisies, fruits (which are the ovaries of angiosperms), nuts, grains, and grasses.

Angiosperms are further split into monocotyledons (monocots) and eudicots. Eudicots include complex flowering plants known as dicotyledons (dicots).

Here is a cladogram that helps me follow when certain characteristics evolved in plants:

Despite ancestors thriving in the ocean, plants are able to survive on land because:

Cell walls help support the plant

Roots/root hairs help absorb water and nutrients

They have stomates, which are able to open to allow gas exchange, and close to prevent excess transpiration.

The existence of cutin, a waxy, water-repellent coating on the leaf that keeps protects the water inside the leaf.

In some plants, their gametes/zygotes form in a protective jacket known as a gametangia to protect them from drying out

The existence of sporopollenin, a tough polymer on the walls of spores and pollen that help them withstand harsh environments

Coatings on seeds and pollen help prevent desiccation (extreme drying)

Dispersion of offspring (etc having bees carry pollen to different plants, having animals eat fruits, spreading the seeds further away, having seeds that are blown away by the wind) to allow genetic diversity, thus protecting the species.

Reduction of the gametophyte (n) generation (since gametophytes provide food for sporophytes, they are a major reason why plants are able to have seeds, which can be spread much further and thus be more successful than spores)

Plants have a tissue known as meristem. This continually divides, thus plants are always growing. There are two kinds of growth.

Primary growth is vertical.

It elongates the plant. This is possible due to the apical meristem, which as stated before, never stops growing.

Root growth happens at the tip! There are 3 zones to note. I labelled them on this diagram.(I’m sorry for my art skills, I tried.)

Secondary Growth is lateral.

(Think of it as an increase in girth.) New cells arise from the lateral meristem. (Thank you scientists for such an easy name to remember, lateral meristem goes with lateral growth. This is the one and only time I can say that.)

In herbaceous plants (non woody plants) like vegetables, and flowers, there is only primary growth, as they only last for a single season, however in plants like trees, you can observe secondary growth by counting the number of rings it has. As it gets older, lateral growth continues, and more rings are added.

The roots of a plant have 3 purposes (the 3 S’) Structure, Storage, and Sucking. (Only word I could think of that started with an s that conveyed the right message.)

The root structure of monocots and dicots are very different.

What these words mean:

The epidermis covers the root. It is modified to allow the root to absorb.

The cortex is filled with parenchyma cells. It contains plastids desitned to store starch.

The stele is necessary for transport. It contains xylem and phloem tissue. It is surrounded by the pericycle, which is where lateral roots come from.

The endoderm surrounds the stele. It is wrapped with the casparian strip, which is selective on what is able to enter the stele. (Think cell membrane)

Absorbtion is important!

The movement of water and solutes across a plant is known as lateral movement. This is aided by two structures.

The symplast is a continuous system of cytoplasm of cells that are interconnected by plasmodesmata (channels along cell walls allowing for transport and communication)

The apoplast is a network of cell walls and intercellular spaces in a plnts body that allow for the extensive extracellular movement of water.

Some plants lack root hairs. Some plants use mycorrhizae, which supply them with water and minerals. These are symbiotic structures that include the plants own roots, mixed with the hyphae (filaments) of a fungus.

Some legumes have a symbiotic bacteria known as Rhizobium. It survives on the nodules of their roots, and is responsible for fixing nitrogen gas in the air.

Roots are cool!

Types of roots:

Taproots- a single large root that births lateral branch roots. In a lot of dicots, the primary root is the taproot. They have many different functions depending on the plant. In some, they tap water hidden in the soil. In some, they are responsible for storage.

Fibrous root systems are found in monocots like grass, and are responsible for support. They hold the plant firmly in place.

Adventitious roots are roots that rise above ground. Aerial roots are found in trees like mangroves that live in swamps, and help aerate the root cells. Prop roots are found in plants like corn, and allow the plant to grow high above ground, as they provide support.

Facts about the stem:

They provide structure, and transport water and minerals

They have vascular tissue running along them in strands called vascular bundles

In those bundles, xylem is found on the inside, phloem is found on the outside and meristem tissue is found in between.

The ground tissue is made of cortex and pith- which are parenchymal tissues(parenchyma is tissue made of living cells with thin primary cell walls) that are used for storage.

The structure of the stem in monocots and dicots are very very different. In monocots, vascular bundles are scattered, while in dicots, they are a ring around the stem.

Each part of the plant leaf has a specialized function. Here they are:

Epidermis: Protection

Waxy cuticle (made of cutin): Minimizes water loss

Guard cells (aka modified epithelial cells- able to photosynthesize): Control the opening of the stomata, also minimizing water loss and allowing for gas exchange

Palisade mesophyll- tightly packed cells: Photosynthesis

Spongy mesophyll- loosely packed cells: Photosynthesis and diffusion/gas exchange in and out of these specific cells

Veins (you find them in the mesophyll): Carry water and nutrients from the soil to the leaves. Carry sugar produced during photosynthesis in the leaves to the rest of the body. Similar to human veins only, don’t have blood (imagine how terrifying that would be, you cut open a carrot and blood comes out)

So what actually are stomates?

Stomates are holes that allow oxygen to be taken out and removed, and carbon dioxide to be taken out and removed (plant cells carry out respiration, and photosynthesis. Oxygen is used in respiration and a byproduct of photosynthesis. Vice versa for Carbon dioxide.)

Stomates have guard cells that work like doors, shutting to prevent too much water from transpiring. This normally occurs at night. When guard cells absorb water, they become turgid, causing them to expand, and curve, opening the stomates. When they lose water, and become flaccid, they close.

[tenth-sentence]

In particular, the guard cell proton-pumping H+-ATPase plays a central role in the regulation of stomatal movements (Figure 16.25; see also Figures 10.6 and 10.7).

"Plant Physiology and Development" int'l 6e - Taiz, L., Zeiger, E., Møller, I.M., Murphy, A.

[whats-in-a-sentence]

In daily opening of stomata in intact leaves, incident radiation, zeaxanthin content of guard cells, and stomatal apertures are closely related (Figure 10.11).

"Plant Physiology and Development" int'l 6e - Taiz, L., Zeiger, E., Møller, I.M., Murphy, A.

[whats-in-a-sentence]

Figure 10.7A asked a patch clamp recording of a guard cell protoplast treated in the dark with the fungal toxin fusicoccin, a well-characterized activator of plasma membrane ATPases.

"Plant Physiology and Development" int'l 6e - Taiz, L., Zeiger, E., Møller, I.M., Murphy, A.

[ijtsrd]

Counting of Stomata from Different Types of Leaves

By Kirti Suthar | Pooja Yadav | Komal Sutariya | Sheeba Menon"Counting of Stomata from Different Types of Leaves" 

Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-6 , October 2017, 

URL: http://www.ijtsrd.com/papers/ijtsrd4717.pdf  

http://www.ijtsrd.com/biological-science/cell-biology/4717/counting-of-stomata-from-different-types-of-leaves/kirti-suthar

international peer reviewed journal, call for paper health science, ugc approved engineering journal

Stomata play a vital role in a plant's life. It helps in the process of Photosynthesis and Respiration. The exchange of gases also occurs through stomata. Thus Stomata is very important part of the plant. Few plants belonging to class Dicot and Monocot were collected to study the number of stomata present in their leaves. Leaves from Herbs, Shrubs, Trees and Climbers were collected for the study. These leaves were collected from wide areas from Ahmedabad city. As the stomata are located on the dorsal surface of leaf, the chlorophyll was scrapped from the dorsal surface. The chlorophyll content should be removed to see the stomata clearly. This chlorophyll content was removed using blade/scalpel and water. The number of stomata was calculated using '˜Micrometer slide'. The scale on '˜Micrometer scale' was 0.01 micrometer. This '˜Micrometer slide' was kept under the microscope and the scale was fixed. After that only the number of stomata was calculated. It was found that '˜Tulsi' had the maximum number of stomata among the dicotyledons whereas '˜Pancreatium sp' had the maximum number of stomata among the Monocotyledons. The stomata were calculated in fresh leaves of collected plants. The number stomata were carried out under '˜Compound Microscope'. The number of stomata is directly related to the enhancement of Physiological process. 

[ijtsrd]

Studies on Stomatal Movement in Dolichus biflorus Linn. (Fabaceae)

By Dr.G.Meerabai | B.Koteswari"Studies on Stomatal Movement in Dolichus biflorus Linn. (Fabaceae)" 

Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-6 , October 2017, 

URL: http://www.ijtsrd.com/papers/ijtsrd2528.pdf  

http://www.ijtsrd.com/biological-science/botany/2528/studies-on-stomatal-movement-in--dolichus-biflorus-linn-fabaceae/drgmeerabai-

peer reviewed international journal, call for paper computer science, ugc approved journal

Usually relative turgor changes which maintain osmotic gradients in the guard cells cause stomatal movements. In many species the dominant participation of K+ in stomatal movements was well established. Organic acids such as malate, citrate, glutamate and aspertate were reported to serve as counter ions of K+ in many species. Both oxidative phosphorylation and photo phosphorylation are potential energy sources. In earlier studies, the functional role of PS II were not clearly understood. Hence the present study is aimed to understand the role of PS II in guard cells of Dolicus biflorus Linn. a Fabaceae member. Influence of PS II electron acceptors and donors such as potassium ferricyanide, hydroxylamine hydrochloride, MnCl2, Sodium ascorbate, diphenyl carbazide, ATP, ADP, ATP + MnCl2 and ADP + MnCl2, MnCl2 + NADP and Hydroxylamine hydrochloride + NADP is studied to understand the role of photo system II on stomatal movements. 

[microanthropic]

Stoma and all