Plasmodesmata in vascular plants and gap junctions and animals are examples of specialized features of the cell. Mechanisms by which transport occurs between cells evolved independently within several eukaryotic clades. Explain, in terms of cellular cooperation, the selective advantages provided by such structures.

Conceptual Physics 12
Problem 43E A stone is shown at rest on the ground. (a) The vector shows the weight of the stone. Complete the vector diagram showing another vector that results in zero net force on the stone. (b) What is the conventional name of the vector you have drawn?

Earth Science 13
Briefly describe the concept of elastic rebound. Develop an analogy other than a rubber band to illustrate this concept.

Chemistry 11
What is the volume (in liters) occupied by 49.8 g of HCl at STP?

Campbell Biology 9
Fossilized stromatolites a. all date from 2.7 billion years ago. b. formed around deep-sea vents. c. resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays. d. provide evidence that plants moved onto land in the company of fungi around 500 million y

Anatomy & Physiology 1
The papillary layer of the dermis is most closely associated with which layer of the epidermis? a. stratum spinosum b. stratum corneum c. stratum granulosum d. stratum basale

Principles of Economics 1
Why is the demand curve with constant unitary elasticity concave?

Urban Economics 8
In Figure 121 , suppose the total achievement curve can be described as Achievement , so the marginal-benefit curve for teachers can be described as marginal bene?t . a. Compute the ef?cient number of teachers for the following teacher wages: {6, 10}. b. Illustrate with a graph like the one sho

Urban Economics 8
Consider a manufacturing firm that occupies two hectares of land. The firm produces 10 tons of output per day and sells its output at a price of $80 per ton. The firm does not engage in factor substitution as the price of land changes. Intraurban transportation is on trucks, with a unit cost of $12 p