Biology - B4 Using food and controlling growth

OCR GCSE (excluding microscopy)

Respiration

Respiration

the process of transferring energy from breaking down glucose. It happens continuously in every cell in every living organism. (Glucose is typically used but other substances such as carbohydrates, lipids and proteins can be used instead)

ATP

energy from respiration cannot be directly used so it is turned into this which stores energy that is used for essential processes like making and breaking molecules, active transport and contracting muscles.

Cellular respiration

A process which includes several different chemical reactions that are controlled by enzymes so are effected by temperature and pH and is exothermic

Aerobic respiration

This happens when there is plenty of oxygen and is the most efficient way of producing ATP - 32 molecules per molecule of glucose. Takes place in the mitochondria of Eukaryotic cells and the cytoplasm of prokaryotic

Respiration rate (practical)

Anaerobic respiration

This occurs when there is very little oxygen in the cytoplasm of animal and plant cells. It produces 2 molecules of ATP. In animals it happens in muscle cells and root hair cells in plants. Animals turn glucose to lactic acid and plants, glucose to ethanol and CO2

Interphase

This is the process before the beginning of mitosis where the DNA is copied and makes an x shaped chromosome (to identical arms)

Prophase

The first phase of mitosis. The DNA increase in size and becomes more visible.

Metaphase

The second phase of mitosis. The chromosomes and their copies move to the centre of the cell.

Anaphase

The third phase of mitosis. chromosomes and their copies are pulled to opposite sides of the cell.

Telophase

The final phase of mitosis. Membrane begins to reform around the chromosomes at each end of the cell

Cytokinesis

The phase following mitosis where the cell splits into two daughter cells.

Estimate the number of cells

Number of cells = 2^n where ‘n’ is the number of divisions

Cancer

This can be caused by uncontrolled cell divisions

Sexual reproduction

This is where two sets of genetic information is used to create offspring

gamete

These contain half the amount of chromosomes and are used in sexual reproduction

diploid cell

a cell that contains two sets of chromosomes

haploid cell

a cell that contains one set of chromosomes

Zygote

A fertilized egg

Fertilisation

When a male gamete fertilizes a female gamete. This creates a full set of chromosomes.

Meiosis

This is a process where the cell divides twice to create 4 daughter, haploid cells. The information splits then so does the cells

Stem cells

These are unspecialized cells that are all the same. They can differentiate to any type of cell. Embryonic ones can specialize into anything but adult ones are only found in the bone marrow and can only differentiate into certain types of cells

Meristems

These are plant stem cells that are found in the roots and shoots and can specialize into anything for as long as the plants live

Adult stem cells

These can be used in medicine by being transferred to a patient to replace cells that are damaged in some way. However these could cause tumors as they divide quickly or illness if the transplanted cells host a disease.

Embryonic stem cells

These can be transplanted into patients however its ethically debated because as the embryos are destroyed in the process.

Auxins

These are plant hormones that promote growth in shoots but inhibit it in shoots

Phototropism

Shoots are positively phototrophic which means auxins are produced faster in the shade causing the plants to grow towards the light. Roots are negatively phototrophic which means auxins are produced faster where there is light which causes the roots to grow away from the light

Gravitropism

Shoots are negatively gravitropic because gravity causes and imbalance of auxins in the tip which causes the lower part of the plant to grow faster and therefore growing upwards. Roots are positively gravitropic which means the auxins are more condensed on the higher part of the plant which means the plant grows downwards.

investigating phototropism

Gibberellins

These are plant hormones that allow plants to germinate and flower. Farmers can use them to allow plants to flower early

Ethene

This is produced by decaying leaves and causes the shedding of leaves and ripening of fruit. This allows farmers to collect their fruit while its unripe and then pump ethne into the vehicle transporting them, causing them to ripen before the supermarket.