Definition of primary phloem and posterior phloem

Phloem. phloem

Vascular plants (ferns and seed plants) transport nutrients in the body, and have complex tissues with functions such as support and storage. The phloem and xylem, which transport water, together form the vascular system. The main function of the phloem is to transport organic matter, that is, to transport the photosynthetic products formed in the leaves to all parts of the plant body.

The phloem is composed of sieve molecules, pachyma cells, and parenchyma cells.

Sieve molecules include sieve cells, the former is found in ferns and gymnosperms, and sieve tubes, the latter is found in angiosperms. A sieve is formed by a series of molecular tips connected to each other. Sieve tube molecules generally only have a primary wall, the cell wall is thicker, on the fresh material section, the thickened cell wall has a pearl luster, called pearlescent wall.

The sieve tube molecule usually contains a viscous protein substance called p-protein (formerly known as mucus).

Generally, there is one or several companion cells next to the sieve molecule, which are from the same mother cell as the sieve molecule in ontogeny, and are also closely related to the sieve tube in physiological function. Structurally, a small sieve tube is not much different from its companions, but when it matures, it is significantly different from each other. The sieve tube molecule and its adjacent companion cells are connected by many plasmodesmata filaments, and the cell wall of some companion cells protrudes into the cavity to become the transmitting cell.

Sieve cells are cells in ferns and gymnosperms that are mainly responsible for transporting nutrients. Sieve cells are structurally similar to sieve tube molecules, but sieve cells are single cells. In gymnosperms there are protein cells similar to the role of companion cells, although these cells are not the same parent cells as the cribriformed cells, but when the cribriform cells lose function, the protein cells also die.

The firmimma cells in the phloem have fibrous and stone cells. The fibers are often distributed in bundles in the phloem of various plants to increase their ability to support, and are called bast fibers. Some plants have stone cells in the phloem that can be bound to fibers, either individually or in groups of cells of varying sizes.

In the secondary phloem, there are usually axial parenchyma cells and ray parenchyma cells. All parenchyma cells have plasmodesmata passing through the primary wall.

According to different **, the phloem can be divided into primary phloem and secondary phloem. The primary phloem is formed by the procambium differentiated from the meristem at the root end or the tip of the stem. According to the sequence of occurrence, it can be divided into primary phloem and posterior phloem.

These two types of primary phloem work together with primary xylem to organize vascular bundles. The rhloem formed during the growth of gymnosperms and most dicots in the roots and stems of gymnosperms and most dicots is called secondary phloem. The secondary phloem, which makes up the majority of the bark, is produced by vascular cambium activity, but much less than the xylem, as is the secondary xylem.

This is due to the lack of formation, and the second is due to the fact that the old phloem is squeezed out and peels off due to peridermal isolation after losing its function, and cannot continue to accumulate like xylem.

The primary phloem is the human skin tissue formed by the apical meristem of the neck, and the secondary phloem is the human formed from this meristem (vascular cambium).

Skin tissue. This is my understanding, sorry I didn't find a specific definition.

The second lecture is the basic genre of film.

1. Documentaries and feature films 1. Documentary Q concept: created with real life.

It is a film art form that uses real people and real events as the object of expression, and processes and displays them, takes the truth as the essence, and uses the truth to arouse people's thinking. Q Purpose: To provide real information about the world outside the film.

Characteristics of DocumentariesExample nThe filmmaker can record the actual occurrence of the event n Can also convey information with the help of charts, maps, or other means (such as "staging"Q Documentaryn typen Through the original material in the archive n Interview or "Speech Type" n "Direct Film": Shooting by trackingThursday, September 26, 20192

1. Documentaries and feature films 2. Feature films Q Feature films present fictional characters, places, or events. Characteristics of real Q feature filmsN The shooting method is fictional, but it may have a certain connection with realityQ The connection and difference between historical films, biopics and documentaries n are all based on real eventsn The former is still fictional in terms of shooting methods, and the events in the film are completely rehearsednHistorical films or biopics convey their views on history in a fictional depiction, and they still belong to feature filmsThursday, September 26, 20193

2. Cartoons vs. live-action films1, CartoonsQ Cartoons and live-action films, in different ways in the production stage (different subjects) Q Types of cartoonsNDrawn cartoonsNCartoons made by cut-outsNCartoons made of clay, models, puppetsExamples of NCG cartoonsThursday, September 26, 2019

3. Experimental Film (Pioneer Film) 1. Experimental Film Q is a kind of film that breaks the rules. In contrast to "dominant" or mainstream films, these films are generally not produced by studios.

The movie genre is divided into: action movies, fantasy movies, comedy movies, horror movies, adventure movies, romance movies, police movies, science fiction movies, war movies, disaster movies, warm movies, epic movies, experimental movies, micro movies, micro animation movies, suspense movies, ** movies, gangster movies, documentary movies, road movies, stream of consciousness movies, animated movies, thriller movies, western movies, character movies, speed car movies, family movies, superhero movies.

It's easy to do, but it needs to have a certain number of connections.

First of all, you need to find a safe and reliable film and television investment platform, and after choosing a reliable platform, you need to select a project. After choosing a film investment project, you can negotiate with the investment company and sign a contract.

Choosing the theme of the movie script can be said to be the soul of the whole movie, if the selected movie does not meet the taste of the current moviegoers, then the box office will definitely not be good after the movie is released, so we must investigate the market to see what type of movie theme will sell well on the market, and comedy themes are more popular according to the current market situation.

Compared with traditional investment products, film investment has the following advantages:

1. The market prospect is good, and the state has issued a total of 153 documents in 7 categories to support the development of the film industry, with policy support.

2. Open and transparent, the real-time box office of the movie can be viewed on Maoyan Professional Edition, and the copyright income will also issue a contract 3. It can make money, as long as you invest in a hit movie, it is easy to reach several times or more than ten times the income, which is incomparable to other investment products.

4. Personal identity and status are improved, the film industry is an independent existence, outsiders want to enter the non-rich or expensive, and after opening up personal investment, everyone can enter the film circle through a movie, and get more access to more resources is just Jiawei on the problem.

5. Trend, film investment will be the investment trend in the next few years.

It's not easy to do, the easiest way to join is to go to Hengdian as a group performer.

1.Submit your personal information to the producer.

The company transfers 10% of the subscription fund to the corporate account and initiates the subscription.

2.After the purchase is approved, the production company mails two copies of the contract.

3.After receiving the contract, sign it and mail one of the copies back to the company4Make up the balance of the subscription and issue a copyright income certificate.

5.The subscription is complete.

Under normal circumstances, the following four points must be met: first, inspect the qualifications of the relevant production company, second, the filing of the relevant film project, third, the payment is a public account, and fourth, the paper contract is signed.

The neighbor and the father broke open the door and found Mustache, who was still carefree playing with toys under the bed.

I think that there was already a tragedy when there was a kitchen **, when Pihu was holding the doll, and ** on the rear camera, only the doll lying on the ground was left, and the content behind it was just describing what might happen! Objective analysis, the microwave oven is not turned off, the gas is not turned off, the iron is not turned off, the water overflows and the power strip and the electric ...... at homeIt's sure it won't last until the night