Oxygen entered the Earth's atmosphere after the appearance of the Great Oxidation Event (Great Oxygenation Event). The Great Oxidation is the first mass extinction on Earth.
The Great Oxidation lasted 2.4 to 2.0 billion years ago.
Oxygen appeared on Earth thanks to cyanobacteria using photosynthesis.
The following is correctly matched with its tissue system is -
4) stele/vascular tissue system
Stele is the the central core/cylinder of the stem and root of a vascular plant, consisting of the xylem and phloem and other supporting tissues. Vascular plants include clubmosses, horsetails, ferns, gymnosperms etc.
I'm pretty sure:
a) pepsin optimal pH: 3 and lipase optimal pH:8
b) No, because the stomach needs to be acidic and have an acidic pH but lipase is considered alkaline because its optimal pH is between 8-14 meaning it's an alkaline.
Not sure if this is any help but I hope it helped a little bit! :)
Answer:
A. Organ
Explanation:
Leaf is an essential part of plant that is involved in photosynthesis and also in exchange of gases. It is made up of epidermis, which is thick one, and is present at lower and upper surface of leaf. Between upper and lower epidermis, mesophyll is present while cuticle is present outside of the epidermis. Xylem and phloem and other connective tissues are arranged in the leaf in such way that it maintains the shape as well as effective transfer of nutrients and water in the leaf. Leaf is an organ, made up of all these tissues to form a complex structure.
Answer:
The nitrogen cycle could not exist without the presence of nitrogen-fixing microorganisms.
Explanation:
As part of the biogeochemical cycles that occur in nature, the nitrogen cycle involves all the organic and non-organic processes that allow the incorporation of this element into the organism of living beings.
Although nitrogen is abundant in nature, in gaseous form, living beings cannot take advantage of it, because they lack the ability to convert this gas into organic nitrogen. Nitrogen-fixing microorganisms -such as bacteria in the soil- turn inorganic nitrogen into organic, that incorporates plants.
Nitrogen-fixing bacteria exist in both soil and plant roots. They are responsible for the conversion of atmospheric nitrogen and ammonium, the product of the degradation of organic matter, into nitrites and nitrates that assimilate the plants. Herbivorous animals obtain this nitrogen from vegetables, and carnivores from them.
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