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Cellular respiration in plants is slightly different than in other eukaryotes because the electron transport chain contains an additional enzyme called Alternative Oxidase (AOX). AOX takes some electrons out of the pathway prematurely - basically the energy is used to generate heat instead of ATP. The exact purpose of AOX in plants is still unclear. Plants ...


42

That molecule is called Geosmin. It is mainly produced 1 by Actinomycetes such as Streptomyces which are filamentous bacteria that live in soil. Other organisms also produce geosmin: Cyanobacteria Certain fungi An amoeba called Vanella A liverwort It is an intracellular metabolite and cell damage is the primary reason attributed to its release. However ...


40

Nice question! Many vegetables taste bitter because they contain compounds known as phytonutrients (Greek phyto = "plant"). There are more than 2500 phytonutrients known, and the most important (and common) ones are categorized as1: Carotenoids: they are the ones that give red/orange/yellow color to some vegetables. They are mainly antioxidants, but some of ...


33

There are 5 answers, all "yes" (though the first one is disputable). First: there exists at least one animal which can produce its own chlorophyll: A green sea slug appears to be part animal, part plant. It's the first critter discovered to produce the plant pigment chlorophyll. The sea slugs live in salt marshes in New England and Canada. In ...


30

The short answer is that as long as the vegetable/fruit is fresh looking - i.e. the cells have not disintegrated - they will be respiring, many cells will be functioning quite normally, and the plant is still technically alive. In cases where the part of the plant we treat as a vegetable is a part intended for reproduction (e.g. a seed, or a tuber like a ...


20

There are quite a few questions and thoughts in there, I'll try to cover them all: First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons). You are correct to assume the C is further used for the growing process; it is used to make sugars which ...


20

There are some other good answers which provide part of the picture, but I think there is a fundamental organising principle which has been missed. Konrad has touched on it in his answer. The reason trees, and most plants, tend to grow equally in all directions is that they have iteratively generated branching and radial symmetry which is controlled in a ...


17

Growth in plants is tightly controlled by auxins – plant hormones. Auxin itself usually has an inhibitory effect on growth [EDIT: see comments and Richard’s answer for correction]. As far as I know there is no active control to restore plant symmetry once it has gone awry (but I could be wrong!) but the inhibitory effect of auxin synthesised at the meristem ...


17

Yes, plants of all sizes can have cancerous growths. Agrobacterium tumifaciens, the causative agent of crown gall disease, produces what is called a tumor. See this link for detailed information on these growths. Alternatively, use a plant physiology textbook to look up the above terms. (Here, is where a textbook is better than a single abstract in PubMed.) ...


16

There are several key ways in which rising atmospheric CO₂ concentrations will affect photosynthesis, and these are related to the different types of photosynthesis. In order to properly answer your question, I'll provide some background about photosynthesis itself. Photosynthesis evolved in a high-CO₂ atmosphere, before the oxygen-enrichment of the ...


16

Bitter taste is sensed by bitter sensitive gustducin receptors (T2R family). There are different types of bitter receptors and they can be triggered by different kinds of ligands. Different classses of phytochemicals that can trigger bitter taste, are reviewed by Drewnowski and Gomez-Carneros (2000). The bitter tasting phytochemicals include phenols, ...


16

Of course they can and do, except in total darkness (spectroscopically, only bands in the far red and in the blue spectra matter - blanking these affects 'total darkness'). In photosynhesis a photon is adsorbed by Photosystem II to break down water into oxygen and protons in solution. Another photon must be adsorbed by Photosystem ! to power the enzymatic ...


15

I wanted to add a little more to the excellent answer above, especially since the OP asks about research into this question in a "real-world context". There is a substantial body of evidence on exactly this question that comes from experiments at "Free Air CO2 Enrichment" (FACE) sites. FACE is an experimental method/technology in which standing ecosystems ...


15

It's not a single grass cell, but this does indeed appear to be a micrograph of a leaf of grass—so it actually contains numerous cells. Here's another image I was able to find with a much more clear description of exactly what you're seeing: Marram grass leaf. Light micrograph of a cross section through a closed (unravelled) leaf of Marram ...


15

Short Answer: Any plant can produce oxygen at night, but plants cannot produce oxygen without light. Longer Answer: It all comes down to spontaneity of a reaction i.e. whether a reaction can occur without input of energy or not. Before we talk about spontaneity, I feel it better to first know about the process we're talking about here. In photosynthesis, ...


14

Plants will be respiring continuously, which is an exothermic process. Therefore the plants will be producing a small amount of heat. The protection from frost may be more a result of the vastly smaller convection current of the coat compared to the atmosphere rather than by reducing any conduction away of heat produced by the plant, however. Keeping the ...


13

It looks to me (although I'd want to use a microscope to check) like the black dots are xylem. When you cut the fruit, you've severed the xylem and also exposed the flat surface. Three main things have then happened: The increased surface area has led to the 'fleshy' part of the fruit contracting as the cells dehydrate. The stiffer, lignified xylem tubes ...


13

It is protection against rapid warming of the cambium layer. A lot of far northern timber has light colored bark which reflects sunlight. The rapid heating from very cold after sunrise can actually damage or even split the bark of dark colored species. This is called sunscalding.


12

In general, plant cells only undergo differentiation at special regions in the plant known as meristems. Two of the primary types of meristem are the root apical meristem (at the tips of roots) and the shoot apical meristem (at shoot tips)^. Within the shoot apical meristem the plant cells divide and begin to differentiate into different cell types (such as ...


12

Disclaimer: This is not my field of research. First, this is not a complete answer to our question. A nice explanation of the current hypothesis of water transport in trees (Dixon-Joly cohesion-tension theory, originally proposed 1894) can be found at The Amazing Physics of Water in Trees but also in Tyree (1997). The key points are that the stoma (leaf ...


12

In my experience (in common with the experience of everyone I've talked to who could be considered an expert on the subject), taking old wood and using that as a scion when grafting new trees rejuvenates them, and they grow as new trees. I'll take apple trees as an example. As you can see from the table here, there is a distinct age after which the tree ...


12

This is a transverse section (T.S.) of leaf blade a sort of Xerophytic (Desert-climate) grasses. such as Ammophila arenaria , Spartina sp, Agropyron sp, Poa pratensis etc. However similar-type-adaptation also seen in other (not-grass) plants. It is T.S. of an object like this. (highly diagrammatic, actually it is much more thinner, needle-like). The 2 ...


12

Ventricaria ventricosa (previously called Valonia ventricosa) is not exactly a single cell. It has a coenocytic structure with multiple nuclei and chloroplasts. As Jasand Pruski correctly guessed the organism possesses a large central vacuole which is multilobular in structure (lobules radiating from a central spheroid region). The entire cell contains ...


12

tl;dr: Sort of? Logically, either red or blue light should be sufficient. Chlorophyll a and chlorophyll b preferentially activate different photosystems, and both photosystems are required in green plants. Practically, we're in luck and someone has actually done the experiment. As the original study reports, plants need a little blue light to grow into ...


11

They don't always. For example, this apple tree grows just outside my window: So far, it hasn't fallen over yet. The reason it grows that way is because all the light is coming from the right side of the picture: the tree leans roughly to southeast, while the building is to southwest of it and casts a shadow on the center of the yard for much of the day. ...


11

Animals and plants are both classified as Eukaryotes, and as such can form large, complex, multi-cellular organisms. There are several major differences at the cellular level that distinguish the 2 Kingdoms (Animalia and Plantae). Without getting technical, the most crucial difference in relation to your question is that plants contain chlorophyll, and as ...


11

This is an interesting topic! Crassulacean acid metabolism is a second CO₂ fixation pathway where CO₂ is absorbed at night. The CO₂ is fixed into maleic acid HOOC-CH₂CH(OH)-COOH which stores some of the CO₂ in the form of carboxyl groups. During the day carboxylases release the CO₂ for fixation during the day. This is an adaptation where the stomata ...


11

The two commonly put-forward explanations for spiral growth of tree trunks related to stress-loading and damage-tolerance. The stress-loading explanation states that spiral-grained trees flex more than straight-grained trees before they break. Flexibility under stress-loading is useful in areas with heavy snowfall (as the tree can flex until the snow falls ...


10

There are a couple of answers to this question. Especially where trees are concerned, you can graft two or more trees onto the same rootstock, or even a single limb into a tree. But if the graft takes, it won't behave too much more differently than just more branches of the same tree. Structurally intertwining them will not be different than if you had ...


10

They are basically conjoined apples which share a common stalk. They are rare but do happen. Here is an article of one discovered in a backyard. conjoined apple discovered in a store (reference) It apparently happens because of bad weather conditions, stress and insect damage. Fused fruits are also found in the case of cherries, watermelons, peaches etc. ...


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