What does the nucleus do?
The nucleus controls all the activities of the cell. It contains the genes on the chromosomes. They carry the instructions for making new cells or new organisms.
What is the cytoplasm?
A liquid gel where most of the chemical reactions needed for life take place.
What does the cell membrane do?
The cell membrane controls the passage of substances into and out of the cell.
What is the mitochondria?
Structures in the cytoplasm where oxygen is used and most of the energy is released during respiration.
What do ribosomes do?
This is where protein synthesis takes place. All the proteins needed in the cell are made here.
What are chloroplasts?
Found in the green parts of the plant and contains a substance called chlorophyll. The chlorophyll absorbs light energy to make food by photosynthesis.
What does a cell wall do?
A cell wall is made of cellulose which strengthens the cell and gives it support.
What is a permanent vacuole?
A space in the cytoplasm filled with cell sap. This is important for keeping cells rigid to support the plant.
What does a bacterial cell consist of?
Cytoplasm and a membrane surrounded by a cell wall. The genes aren't in the distinct nucleus. Many also have plasmids which are small circular bits of DNA. The flagella is a long protein strand which propels the bacteria.
What is yeast?
A single celled organism with each cell consisting of a nucleus, cytoplasm and a membrane surrounded by a cell wall.
Facts about yeast
Yeasts reproduce by asexual budding which means a new yeast cell grows out from the original cell. Yeasts are specialised to survive long periods without oxygen. Yeasts can respire aerobically and anaerobically. Fermentation occurs when yeasts respire anaerobically.
Specialised cells may be used to carry out a particular task.
Examples of specialised cells
Fat cells- small cytoplasm and large amounts of fat. Few mitochondria as the cell doesn't need lots of energy. They can expand. Root hair cells- root hairs increase the surface area for water to move into the cell. The root hair cells have a large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair cell.
What is diffusion?
Diffusion is the spreading out of the particles of a gas or of any substance in a solution from an area of high concentration to an area of a lower concentration.
Rates of diffusion
If there is a big difference in concentration between two areas, diffusion will take place quickly. The bigger the difference the steeper the concentration gradient. Temperature- An increase in temperature means the particles in a gas or solution move quickly. Surface area- an increase in surface area means there is more room for diffusion to take place.
Diffusion in living organisms
Oxygen for respiration passes from the air into your lungs. From there, it gets into your red blood cells through the cell membranes by diffusion. Oxygen moves from a high to low concentration gradient.
What is a tissue?
A group of cells with similar structure and function.
What is an organ?
Organs are groups of tissues and one organ may contain several types of tissues.
Examples of tissues
Muscular tissue- can contract to bring about movement Epithelial tissue- covers the outside of the body as well as internal organs Glandular tissue- secrete substances Epidermal tissue- cover the surfaces and protect them Mesophyll tissue- contains lots of chloroplasts and can carry out photosynthesis.
What are two functions of the pancreas?
Makes hormones to control blood sugar Makes some of the enzymes that digest our food
What are organ systems?
Groups of organs designed to carry out major functions.
Adaptations for exchange:
•There is an exchange of gases in the lungs. •Digested food moves from the small intestine into the blood. •Many different substances are filtered out of the blood into kidney tubules.
•Leaves contain Mesophyll tissue and photosynthesis occurs here. •Stems support the plant. •Roots take up water and minerals from the soil. •Phloem transports dissolved food. •Xylem transports water and minerals.