Companion cells in minor veins of mature leaves. All three cell types have dense cytoplasm and abundant mitochondria, there are three types companion cells  present in column A while its characteristics given in column B;

             COLUMN A                                                             COLUMN B

A) Ordinary companion cells              i) appear well suited for taking up solutes via cytoplasmic connections numerous plasmodesmata connecting them to bundle sheath cells. Its having numerous small vacuoles, as well as poorly developed thylakoids.

 

B) Transfer cells                                    ii) have chloroplasts with well-developed thylakoids     and a cell wall with a smooth inner surface. The number of plasmodesmata connecting ordinary companion cells to surrounding cells.

C) Intermediary cells                          iii) the development of fingerlike wall in growths, particularly on the cell Walls. These wall ingrowths greatly increase the surface area of the transfer cell’s  plasma membrane, few plasmodesmata connect this type of companion cell to any of the surrounding cells except its own sieve element.

Which of the following correct combination;

#Question id: 10631

#Unit 10. Ecological Principles

To estimate the number of foxes m an area, a researcher conducted a mark-recapture survey. In the fast survey, he caught and marked 90 foxes. In his second survey a week later, he caught 120 foxes of which 40 were marked (recaptures). If you are told that the actual number of foxes in this area is 400, which of the following is a plausible explanation for the anomaly in the researcher's data? 

#Question id: 10632

#Unit 10. Ecological Principles

Three different population growth pattern related to population density are shown in figure

#Question id: 10633

#Unit 10. Ecological Principles

Following some characteristic feature of r selected species

A. late maturity

B. Provision of parental care

C. High mortality during early stages of life

D. large clutch size

What is the above combination is correct?

#Question id: 10634

#Unit 10. Ecological Principles

Consider a population which is changing from one generation to the next as per the equation N(t) = R*N(t-1), where N(t) represents the size of the population at time t and R is a constant growth parameter. Under what condition is the population likely to go extinct?

#Question id: 10635

#Unit 10. Ecological Principles

Three important biological parameters – generation time, per capita growth rate (r) and clutch size are a function of the organism‟s body size. Which of the curves (a) or (b) represents the correct relation of each of the parameters to body size?

#Question id: 10636

#Unit 10. Ecological Principles

The demographic transition model depicts demographic changes from high- to low-level births and deaths in five stages

Stage 1 is characterized by total population numbers are low and the high birth rate is balanced by the high death rate.

B) Stage 2 is characterized by high population growth rate is results of high birth rate however, decline death rate

C) Stage 4 is characterized by decline in the proportion of the population in the reproductive age group and these changes stabilizes population size

D) Stage 3 is characterized by falling birth rates and death rates and population growth rate is zero due to the less numbers of people in the reproductive age group