Biology GCSE

• Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells.
• Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.
• Stem cells can be used to clone rare species to protect from extinction.
• Stem cells from adult bone marrow can form many types of cells including blood cells.
• Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant.
• The use of stem cells has potential risks such as transfer of viral infection, and some people have ethical or religious objections.
• Stem cells can be used to produce clones of crop plants with special features such as disease resistance.
• In therapeutic cloning an embryo is produced with the same genes as the patient.
• Treatment with stem cells may be able to help conditions such as diabetes and paralysis.
• Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment.
• Organs are organised into organ systems, which work together to form organisms.
• Plants require ions for healthy growth.
• Active transport also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration.
• Cells are the basic building blocks of all living organisms.
• Organs are aggregations of tissues performing specific functions.
• Sugar molecules are used for cell respiration.
• A tissue is a group of cells with a similar structure and function.
• Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil.
• Cells in different organisms have structural differences that enable them to perform specific functions within the organism.
• Bacterial cells (prokaryotic cells) are much smaller in comparison and have a cell membrane surrounded by a cell wall.
• Cell differentiation is the process where an organism's cells differentiate to form different types of cells as it develops.
• The genetic material in bacterial cells is not enclosed in a nucleus but is a single DNA loop and there may be one or more small rings of DNA called plasmids.
• Cells can be specialised to carry out a particular function, such as sperm cells, nerve cells and muscle cells in animals, and root hair cells, xylem and phloem cells in plants.
• Plant and animal cells (eukaryotic cells) have a cell membrane, cytoplasm and genetic material enclosed in a nucleus.
• These differences in cells are controlled by genes in the nucleus.
• Cells can be compared in terms of their scale and size, and order of magnitude calculations can be made, including the use of standard form.
• For an organism to grow, cells must divide by mitosis producing two new identical cells.
• Microscopy techniques have developed over time and electron microscopy has increased understanding of sub-cellular structures.
• If cells are isolated at an early stage of growth before they have become too specialised, they can retain their ability to grow into a range of different types of cells.
• Stem cell technology is a new branch of medicine that allows doctors to repair damaged organs by growing new tissue from stem cells.
• Plant cells often have chloroplasts, a permanent vacuole filled with cell sap, a cell wall made of cellulose, and may have root hairs.
• Most animal cells have a nucleus, cytoplasm, a cell membrane, mitochondria, and ribosomes.
• Cells are the basic unit of all forms of life.
• Required practical activity 2 involves investigating the effect of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibition.
• Required practical activity 4 involves using qualitative reagents to test for a range of carbohydrates, lipids and proteins.
• Required practical activity 3 involves investigating the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue.
• Losses of biomass are due to not all the ingested material being absorbed, some is egested as faeces, and some absorbed material being lost as waste, such as carbon dioxide and water in respiration and water and urea in urine.
• Trophic levels can be represented by numbers, starting at level 1 with plants and algae.
• Food security is having enough food to feed a population.
• Level 4: Carnivores that eat other carnivores are called tertiary consumers.