## What is reaction-diffusion patterns?

The reaction-diffusion model describes the emergence of periodic patterns such as spots, stripes, and maze on the surface of animal coat through chemical interaction among cells [34]; see Figure 6.5. In the reaction-diffusion model, two hypothetical chemicals, called morphogens (activator and inhibitor) are considered.

## What is the chemical equation for diffusion?

Two-component reaction–diffusion equations with f (u) = λu − u3 − κ which describes how an action potential travels through a nerve.

**What is the Turing equation?**

Turing came up with two equations that model what kinds of patterns would be produced as both the concentration of the two chemicals and the speed at which they diffuse changes. However, it was incredibly difficult to solve these complex equations with the primitive computing machines around at the time.

### What is diffusion distance?

The diffusion distance is related to the probability of travelling on the surface from one point to another in a fixed number of random steps [29–31]. The diffusion distance is an average length of paths connecting two points on the shape, while the GD or ID is the length of a shortest path.

### What is diffusion length?

The diffusion length of a carrier type in a material can be defined as the average distance that an excited carrier will travel before recombining. The diffusion length can be defined as follows: L D = Dτ , where D is the diffusion coefficient and τ is the lifetime of the excited carrier.

**What is diffusion chemistry?**

Diffusion is defined as the movement of individual molecules of a substance through a semipermeable barrier from an area of higher concentration to an area of lower concentration [34].

## What are 2D shapes?

2D Shapes: Two dimensional shapes are defined as plane figures consisting of length and breadth. We come across 2d shapes in our day-to-day life in the form of circle, triangle, square, rectangle and pentagon.

## What is an example of a two-dimensional shape?

For example, a sheet of paper is two-dimensional in shape. It consists of a length and a width but does not have any depth or height. Some common 2D shapes are square, rectangle, triangle, circle, and hexagon.

**What are the angles of 2D shapes measured in?**

The angles of 2d shapes are measured in degree. There are different types of 2d shapes such as circle, triangle, rectangle, pentagon, square etc. We can say that all the 2d shapes are polygon except for circles. Polygons have a closed structure with sides whereas, circle consists of a curved shape.

### What are the different shapes in science?

In general, we can see shapes such as triangles, squares, and circles everywhere around us. Moreover, shapes such as a sheet of paper, have only length and breadth. Thus such shapes are 2D or two-dimensional. While other shapes such as the shape of a house, have length, breadth, and height.