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gas exchange (plants) change m gazeux (plantes)

Gas exchange (in plants). (A) Land plants: Gas exchange occurs in leaves and young stems through pores in the epidermis called stomata. Exchange occurs in young roots by diffusion between the roots and the air in the soil. As for older stems and roots in which the bark has formed, gases are exchanged through gaps in the bark called lenticels.

(b) Aquatic plants: Not for submerged plants

Section of a stem showing the lenticule
Air circulates inside
Lenticular skin
Air space
Dead cells
Cortex cells

Like pondweed, there are no changes, and gas exchange occurs by diffusion across cell membranes. As for aquatic plants with leaves floating on the surface of the water, such as the water lily, they have stomata on the upper surface of the leaf only.

(c) Non-green plants. These plants, such as mushrooms and respiration, do not create light, but they breathe, photosynthesize, and gas exchange occurs by diffusion between the plant cells and the surrounding air.

gas - exchange surfaces
surfaces fpl change gazeux

Gas exchange surfaces Gases are exchanged across
Surfaces have the following features:
(a) Large surface area for maximum exchange
For gases.
(b) Thin surface allows easy diffusion. (c) Wet surface, since gas exchange takes place in the solution.

(d) In animals, a surface with a good blood supply, since the gases in question are transported through the blood.


gastric
gastrique

Contagious. Description of the body parts and their related functions
With the stomach.


genes
genes mpl

Genes are subunits of chromosomes composed of pieces of DNA that control the hereditary characteristics of organisms. Genes consist of up to a thousand base pairs in a DNA molecule, and the specific sequence of these pairs represents encoded information. This is what is known as the genetic code, which determines the types of proteins that cells synthesize, especially enzymes, which then dictate the structure and function of cells and tissues, ultimately reaching the structures and functions of organisms. That is, the cell or organism is nothing but the product of the genes it inherited (and the environment in which it lives).

The genetic code is the arrangement of nitrogen base pairs in DNA. Each group of three adjacent base pairs (triads) is responsible for linking amino acids to each other to form a protein inside the cell. The sequence of amino acids, their types and numbers determine the nature of proteins, which determines...
In turn, the characteristics of the cell.

For example, the basic triplet GTA encodes the amino acid histidine, while GTT encodes the amino acid gutamine.

Let us consider two fruit flies (Drosophila). Gene x controls the body color of the first, while gene 7 controls the body color of the other.

Gene
Gene Y Enzyme Y catalyzes Y pigment
Dye x light body
Y staining produces a dark colored object


genetics
génétique f

Genetics . The study of heredity, which is the transmission of characteristics from parents to offspring via genes in chromosomes. Genetics is investigated by conducting breeding experiments and then comparing the characteristics of parents and offspring. Gregor Mendel was the first to conduct these experiments in the 1860s using pea plants (see monohybrid inheritance). incomplete dominance and backcross.


genotype
genotype m

Genotype The genetic structure of the organism, i.e
The special set of antigen alleles in each cell. Genotypes in breeding experiments are represented by symbols, where uppercase letters indicate dominant alleles and lowercase letters indicate recessive alleles. Look . monohybrid inheritance.


genus
genre m

sex. A unit used in the classification of living organisms that consists of a number of similar species.


geotropism
geotropism m

Geotropism is a form of tropism related to gravity, where the branches and shoots of plants grow away from the direction of gravity. It has negative geotropism, but most roots have positive geotropism.