6. Nutrition

Nutrition

Core

Define Nutrition

Nutrition is the ability of an organism to take in nutrient molecules containing raw materials or energy for growth/tissue repair and then absorbing/assimilating them. An example could be a plants ability to take in Magnesium Ions from soil and use them to produce Chlorophyll.

5. Enzymes

Enzymes

Core

Define the term catalyst

Define the term Enzyme

Investigate and describe the effect of changes in 

temperature and pH on enzyme activity

Extended

Explain enzyme action in terms of the ‘lock 

and key’ model

Explain the effect of changes in temperature 

and pH on enzyme activity.

Describe the role of enzymes in the 

germination of seeds, and their uses in 

biological washing products and in the food 

industry (including pectinase and fruit juice)

Outline the use of microorganisms and 

fermenters to manufacture the antibiotic 

penicillin and enzymes for use in biological 

washing powders

Describe the role of the fungus Penicillium in 

the production of antibiotic penicillin

A catalyst is a substance which speeds up a chemical reaction, an enzyme is an example of one of these. Catalysts are also not changed by reactions.

An enzyme is a protein and biological catalyst which speeds up chemical reactions in the body, without them, reactions would take place far to slow for life to take place.

Enzymes have an optimum PH and Temperature to work in, any change to this could result in Enzymes being denatured which means that it has basically changed shape so much, that it's substrate can no longer fit into it. The optimum Temperature for enzymes is 37 degrees Celsius which also just happens to be our internal body temperature.

Extended

The lock and key method is fairly easy to understand (consult picture above right) In essence, an enzyme is like a lock and a certain substrate is that enzyme's matching key. The substrate (molecule being worked on) 

attaches itself to the enzyme's 

active site. This is now known as an enzyme - substrate complex, after a while the enzyme will change shape slightly and release products.

As temperature increases past an enzymes optimum working temperature the rate of reaction will slow down and eventually (if temperature keeps increasing) the enzyme will denature and will no longer fit any substrate.

4.3 Osmosis (Unfinished)

Osmosis

  Core

• Define osmosis

• Describe the importance of osmosis in the 

 uptake of water by plants, and its effects on 

 plant and animal tissues

  Extended

• Describe and explain the importance of a 

  water potential gradient in the uptake of water 

  by plants

Osmosis can be define as the net movement of water molecules from an area of low water concentration to that of a higher one.

Osmosis is clearly very important to plant as, without it obtaining water would be either very difficult or impossible. Osmosis provides a medium for which water can be simply retrieved from nearby soil by root hair cells.

A water potential gradient ensures that no water is lost from root hair cells when it is being absorbed. It also makes sure that water does not simply leak out of cells, 

4.2 Active Transport (Unfinished?)

Active Transport

Extended

• Define active transport
• Discuss the importance of active transport
as an energy-consuming process by which
substances are transported against a
concentration gradient, e.g. ion uptake by root
hairs and uptake of glucose by epithelial cells
of villi

Active Transport is when a substance is taken from an area of lower concentration to that of higher concentration against its concentration gradient, as its name suggests this process requires energy released from respiration.

Without the possibility of Active Transport plants would not be able to take in certain minerals found in small amounts in soil near them, this would cause them to wilt and eventually die.

4.1 Diffusion

4.1 Diffusion

Core

• Define Diffusion

• Describe the importance of diffusion of gases 

and solutes and of water as a solvent

Diffusion can be defined as the net movement of particles from an area of high concentration to one of low concentration down a concentration gradient. An example could be the diffusion of gasses from the air into leaves through Stomata. In the air there is a higher amount of Carbon Dioxide than there is in leaves. Therefore the C02 moves down its concentration gradient (High-Low) from the air, through the stomata and into the leaf. We say that the C02 has diffused into the leaf.

Diffusion is incredibly important to life. When we respire we produce Carbon Dioxide and this must be excreted as it is bad for cells and would damage them, C02 rich blood is taken to the lungs and diffused out of the blood by alveoli, it is then excreted by the lungs. Without diffusion, manylife processes could not take place.

Size of Specimens

Size of Specimens

Levels of Organisation

Levels of Organisation

Core
• Relate the structure of the following to their
functions:
• ciliated cells – in respiratory tract
• root hair cells – absorption
• xylem vessels – conduction and support
• muscle cells – contraction
• red blood cells – transport

Define:
• tissue
• organ
• organ system

Ciliated Cells - These are cells with tiny cilia. Many cilia can be found in your throat and are generally used for pushing substances along e.g mucus when you have a cold. They can also be found on the lining of the intestines but that is more for the absorption of enzymes (discussed later)

Root Hair Cells - These Cells absorb water and nutrients from surrounding soil to benefit the plant. It absorbs water by process of Osmosis, down a water concentration gradient.

Xylem Vessels - Once water has been absorbed into the plant root hair cell, it proceeds to the Xylem. At the top of the Xylem is a low pressure whereas at the bottom is a higher pressure, this causes water to flow up the Xylem to the rest of the plant.

Muscle Cells - These are the cells which make up muscles. They are generally used for movement/contraction. Cells make up a tissue and the main feature of muscle tissues is their ability to shorten/contract to promote movement.

Red Blood Cells - The main function of Red blood cells is to transport Haemoglobin. Once Oxygen has gone through the Lungs, it is Oxygenated and contains Haemoglobin, it takes this Haemoglobin to other cells around the body and oxygenates them. Red blood cells contain no nucleus and have a biconcave shape, both of these features allow for a larger surface area in which to carry Haemoglobin. Red blood cells are also very small, which means they can fit through even the tiniest of Capillaries and oxygenate every cell in the body.

Tissue -  a group of cells with similar structures, working together to perform a shared function.

Organ - This can be defined a as a group of tissues working together to perform a single bodily function. The lungs oxygenating blood could be seen as one example.

Organ System - This can be defined as a group of organs working in a system to carry out body functions. The organs involved must have similar functions and work towards the same goal for example, all the organs in the Circulatory System.