Search our library of A Level questions

Top answers

All subjects

A Level

Outline the structures involved in the mammalian gaseous exchange system. For each structure explain how it increases the efficiency of gaseous exchange [6 marks]

Trachea- c shaped cartilage provides structure and support, goblet cells and ciliated epithelium, secrete mucus to trap dust and pathogens and waf...

Answered by • Biology tutor

11451 Views

A Block of mass 2kg is on an a smooth inclined plane where sin@ = 3/5 at point A. Point B is 5 meters down the incline. Find the time it will take for the block to reach point given it is at rest at point A.

So to start with draw a free body diagram of a block on the slope at point A with the forces acting on it which will be the downward force of mass x g (2g) due to gravity and the reaction force 2gcos@. Th...

Answered by Harry S. • Maths tutor

3172 Views

Why is the definite integral between negative limits of a function with positive values negative even though the area bound by the x-axis is positive? for example the integral of y=x^2 between x=-2 and x=-1

Referring back to the definition of an integral, it is the sum of small elements on the x-axis (dx) multiplied by the value of the function at that point (y) commonly expressed as the sum of ydx. Since x ...

Answered by • Maths tutor

3427 Views

what is electronegativity and explain the trend in electronegativity as we go down the group?

Electronegativity is the power of an atom to attract electrons in a covalent bond towards itself. As we go down the group, electronegativity decreases because the atomic radii increases. The atomic radii ...

Answered by • Chemistry tutor

5049 Views

What is Differentiation?

Differentiation is finding the derivative of an equation. The easiest way to understand it is to look at examples and then practice on more complex questions. These for examples show the three basic princ...

Answered by Zoé M. • Maths tutor

3026 Views