Answer:
A, cell wall structure
Explanation:
B.
vessels
C. companion cells
Answer: The correct answer is- C) Companion cells.
Phloem tissue is a complex conducting tissue that is present in the vascular plants and responsible for the transport of organic compound such as carbohydrates and proteins from leaves to the rest part of the plant.
The various components of phloem tissue are- Sieve element, Companion cells, phloem parenchyma, phloem fiber.
Companion cells are specialized cells ( present in association of sieve element) that perform various metabolic reactions and responsible for cellular activities. They help in loading and unloading of carbohydrate into sieve element.
Answer:
True
Explanation:
Koch's postulates was proposed to show a causative relationship between a microbe and a disease.
Koch's postulates
•The microorganism must be present in large quantity in all organisms affected by the disease, but should not be seen in healthy organisms.
Koch abandoned this due to his discovery of asymptomatic carriers of cholera and of typhoid fever. Asymptomatic or subclinical infection carriers are seen in diseases, especially viral diseases.
•The microorganism must be seperated from a diseased organism and nutured in pure culture.
This can suspended for specific microorganisms or entities which(at the current time) can't be nutured in pure culture. Viruses uses host cells to grow and replicates and not in pure culture.
•The cultured microorganism should lead to disease when it infects a healthy organism.
It says "should", not "must".
NOTE: NOT ALL organisms introduced to an infectious agent will be infected which may be due to certain factors like general health and good immune functioning; vaccination; or genetic immunity. Its best explained using the resistance to malaria as a result of presence of at least one sickle cell allele.
•The microorganism must be reisolated from the inoculated, diseased experimental host and observed as being identical to the basic specific causative agent.
A single pathogen may lead to several disease conditions. A singualr disease infection may be due to several different microorganisms. While some pathogens cannot be cultured in a pure culture in the lab, others can infects humans.
The answer is hypertonic
Answer: hypertonic
Explanation: