| Name the two main classes of cells. | Eukaryotic and prokaryotic |
| Describe the main features found in prokaryotic cells. | Cytoplasm, cell membrane, cell wall, loop of DNA and plasmids |
| Describe the main features found in eukaryotic cells. | Cell membrane, cytoplasm and nucleus |
| Give an example of a eukaryotic cell and a prokaryotic cell. | Eukaryote: e.g. palisade cell, white blood cell, nerve cell etc. Prokaryote: bacteria. |
| What is the function of the nucleus? | Control the functions of the cell and is the location of chromosomes in eukaryotic cells. |
| What is the function of the ribosome? | Protein synthesis. |
| What is the function of the mitochondria? | Site of aerobic respiration. |
| What is the function of the chloroplast? | Site of photosynthesis. |
| What is the function of the cell membrane? | The selective transport of substances in and out of the cell. |
| What is the function of the cell wall? | Supports the cell. |
| What is the function of the vacuole? | Involved with keeping plant cells turgid by osmosis. |
| Explain how a scientist could distinguish between an animal and plant cell. | A plant cell has a cell wall, chloroplasts and a vacuole in addition to the parts of an animal cell. |
| Calculate the order of magnitude between a eukaryotic cell (100_m) and a prokaryotic cell (1_m). . | 2 |
| Describe how the structure of a nerve cell relates to its function. | It is long to connect to the central nervous system. It is surrounded in fat to insulate the electrical signal. |
| Describe how the structure of a sperm cell relates to its function.Ê | The sperm cell has a tail to allow it to swim. It is packed with mitochondria to provide energy.Ê The nucleus contains only half the chromosomes. |
| Describe how the structure of a muscle cell relates to its function.Ê | The muscle cells contain fibres to contract. It has many mitochondria to provide energy. |
| Describe how the structure of a root hair cell relates to its function. | The root hair cell has thin projections which increase the surface area to volume ratio of the cell to allow efficient transport of water by osmosis. |
| Describe how the structure of xylem relates to its function.Ê | Xylem consists of hollow tubes strengthened by lignin to allow the transport of water. |
| Describe how the structure of phloem relates to its function. | Phloem is composed of tubes of elongated cells with sieve plates.Ê Cell sap can move from one phloem cell to another through the sieve plates in the end cell walls. |
| Describe the stages of the cell cycle and mitosis. | The cell will grow and increase the sub cellular structures such as ribosomes and mitochondria. The DNA will divide to form two copies of each chromosome. In mitosis the chromosome pairs are pulled apart to each end of the cell. The cytoplasm and cell membrane then divide to form two identical cells. |
| Explain the importance of mitosis in a multicellular organism. | Mitosis is important in the growth and development of multicellular organisms. |
| Describe how technological advances in microscopes have improved our understanding of the cell. | Light microscopes allowed for the discovery of cells and electron microscopes allowed for the discovery of organelles within the cell. |
| Compare the light microscope and electron microscope with regards to magnification and resolution. | Electron microscopes have high magnification and high resolution (detail). Light microscopes have low resolution and low magnification. |
| What is the formula to calculate magnification. | Magnification = size of image / size of real object |
| Describe how the genetic material is organised in eukaryotic cells. | Genetic material is made from DNA and organised in to chromosomes. |
| Describe the stages of the cell cycle and mitosis. | The cell will grow and increase the sub cellular structures such as ribosomes and mitochondria. The DNA will divide to form two copies of each chromosome. In mitosis the chromosome pairs are pulled apart to each end of the cell. The cytoplasm and cell membrane then divide to form two identical cells. |
| Explain the importance of mitosis in a multicellular organism. | Mitosis is important in the growth and development of multicellular organisms. |
| What is a stem cell? | It is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can develop by differentiation. |
| Describe a use of human embryonic stem cells. | Stem cells from embryos can be cloned and made to differentiate into most different types of human cells |
| Describe a use for adult stem cells from bone marrow. | Stem cells from bone marrow can form many different types of cells including blood cells. |
| What is meristem tissue? | Meristems tissue is found in plants and can differentiate into any type of plant cell throughout the life of the plant. |
| Name two potential conditions that embryonic stem cells may help to treat in the future. | Diabetes and paralysis |
| Describe therapeutic cloning.Ê | An embryo is produced with the same genes as the patient. The stem cells removed from the embryo will not be rejected by the patientÕs body so may be used for medical treatment. |
| Name some disadvantages of using embryonic stem cells.Ê | Risk of transfer of viral infections.Ê Religious or ethical objections to using embryos for research. |
| Name two uses of stem cells from meristems. | Rare species can be cloned to protect from extinction and crop plants with special characteristics such as disease resistance or drought resistance, can be cloned to produce large numbers of identical plants for farmers. |
| What is diffusion? | The net movement of particles from an area of higher concentration to an area of lower concentration. |
| Give two examples of diffusion. | Gaseous exchange of carbon dioxide and oxygen in the lungs and muscles, the removal of urea from cells into the blood. |
| Name three factors which affect the rate of diffusion. | The difference in concentration (concentration gradient), the temperature and the surface area of the membrane. |
| Describe the surface area to volume ratio of a single cell organism. | A single cell organism has a large surface area to volume ratio. This allows the transport of substances in and out of the organism to meet its metabolic needs. |
| Name five exchange surfaces found in animals and plants. | Small intestine, lungs, gills, roots and leaves. |
| Name four ways the efficiency of an exchange surface can be increased. | Having a large surface area, a thin membrane (for a short diffusion path), an efficient blood supply (animals), being ventilated (animals for gaseous exchange). |
