Stem Cells and Totipotency

Explain how the dark and light bands are formed by light reaching the screen from the two slits of the double slit

I think this is more of a Physics question but certainly has implications in Biology. The phenomenons taking place are diffraction and interference. Of course, couple of things have to first be fulfilled for diffraction to take place the size for the slit relative to the wavelength being one of them etc(if you want a more detailed answer just DM me and I will be happy to explain further). Then relative to the angle formed between the two slits relative to the point on the screen a maxima(“light band”)or a minima(“dark band”) is formed(I am talking about intensity) due to interference of the waves from the two slits. If you have further questions feel free to ask.

Why do claw machines fling their toys inwards?

This is the trick claw machines use in order to release as little product as possible compared to the influx of money they receive. In simple terms this feature allows businesses to make the money from claw machines.

What is the role of trade unions? And why is there a decline in trade union memberships in UK

The role of trade unions is to act as a collective voice for workers in regards to fair pay and working conditions. Trade unions have been on the decline as successive governments, starting under Thatcher, have passed legislation in order to reduce their powers. Subsequently many young people enter the workforce today with little understanding of what a union is and how they could benefit from being a member of one.

An athlete trains to run a marathon. The surface area of each of the athlete’s lungs has increased to 80 m2. Give one way in which this increase will help the athlete.

An increased surface area means the athletes would be able to perf use the blood with oxygen more richly leading to a greater supply of oxygen rates blood to effector muscles and thus an enhanced performance

Why the peritubular beds are low in pressure ?

Resorption of water and sodium is governed by the starling forces surrounding the peritubular capillaries. Several factors can modify the peritubular starling forces and in so doing can modulate net fluid resorption by the kidneys. Because blood in the capillaries has passed through the glomerulus and a proportion of the fluid has been filtered into the nephron, peritubular capillary blood has a high oncotic pressure and a low hydrostatic pressure. In contrast, the interstitial fluid oncotic pressure and hydrostatic pressure are relatively low. The oncotic pressure of the peritubular capillaries is actually relatively high because a significant percentage of the vascular fluid is filtered out in the glomerulus and into the tubule, leaving a higher concentration of plasma proteins in the blood entering the peritubular capillaries. It is the hydrostatic pressure of the peritubular capillaries is relatively low because much of the intravascular pressure is lost after blood passes through the afferent and efferent arterioles. Overall, the balance of forces is toward movement of sodium and water into the peritubular capillaries.

Describe the role of stem cells in multicellular organisms

Good question! To start, a stem cell is a cell with the ability to self-renew indefinitely. This means they can divide themselves unlimited amounts of times. This is unlike other normal cells which have a limited number of cell divisions. Stem cells are important to maintain ALL of our cell populations. For example, at the bottom of our skin's outer layer, the epidermis, are a one cell thick layer of skin stem cells. These divide, remain in their positions on the bottom whilst their daughter cells move forward towards the skin surface. Eventually they die when they reach the surface of our skin. They are also important for making the cells of our blood and immune system, as well as helping repair, regeneration and healing of tissue after injury. They form our nerves, bones, fat stores as well as sex cells, the sperm and ovum. The rest of my answer is a little advance, so maybe only read if you are an A-Level or University student! Many people think that pluripotent cells, are always stem cells. But this isn't true! For example there are early embryo cells at the "morula stage" that can give rise to all adult (somatic) cells, meaning they are pluripotent, but they are not stem cells as they do not have the ability to self renew. It is important to mention also the difference between cancer cells and stem cells, as an important hallmark of cancer is gaining the ability of unlimited self renewal. the main difference is that stem cells also ALWAYS retain their normal phenotype, meaning they cellular biology does not change. Cancer cells show different phenotypes, meaning they look different under a microscope. They are different to the normal tissue at a cellular level. If you would like to learn about this in a more simple way, or hear about the fine complex details, message me! Happy to help. Thanks, Ben.