Biology Flashcards
What is the difference between Glycogen, Glucose, Glucagon and Glycerol.
Glucose: Sugar
Glycogen: Carbohydrate - how glucose is stored in animals
Glycerol: Breakdown product of lipids
Glucagon: Hormone that brings super levels back up (it does the opposite of insulin
What is the difference between a prokaryote and a eukaryote?
Prokaryotic cells = Bacterial cells:
Much smaller in comparison.
They have cytoplasm and a cell membrane surrounded by a cell wall.
The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids.
Eukaryotic cells = Animal cells and plant cells
Bigger than bacterial / prokaryote cells
Genetic material enclosed in a nucleus
Have a cell membrane and cytoplasm
What do animal cells have and what are these sub cellular structures’ functions?
Cytoplasm - Where chemical reactions happen
Nucleus - Contains DNA
Mitochondria - Respiration
Ribosomes - Protein synthesis (making of protein)
Cell membrane - Controls what goes in and out of the cell
What do plant cells have that animal cells don’t have?
Chloroplasts containing chlorophyll
Cell wall made of cellulose
Permanent vacuole filled with cell sap
What is the cell wall made of?
Cellulose
What is the function of chloroplasts?
Photosynthesis - to make glucose
Are able to absorb sunlight energy
Chlorophyll
What happens in the growth phase of the cell cycle?
Genetic material is doubled
It increases the number of sub-cellular structures such as ribosomes and mitochondria.
What happens once the growth phase is completed?
Mitosis - cell division.
Describe the overall process of mitosis.
- Chromosomes have been duplicated during the growth phase
- Nuclear membrane breaks down
- Chromosomes can align along the centre of the cell
- Sister chromatids are torn apart and pulled to opposite poles of the cell
- Cytokinesis happens - the cell divides into two cells
Describe the products of mitosis?
x2 genetically identical, diploid daughter cells
Why is mitosis important?
Growth and repair
What is the definition of a stem cell?
A stem cell 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 arise from differentiation.
Where can stem cells be found in humans?
Embryos
Adult bone marrow contains stem cells that can differentiation into blood cells (red or white)
Where can stem cells be found in plants?
Meristem - stem cells here can differentiate into any type of plant cell, throughout the life of a plant
Why are we interested in stem cells?
Because treatment with stem cells may be able to help conditions such as diabetes (by producing new pancreas cells that can make insulin) and paralysis (by producing new nerve cells).
What is therapeutic cloning?
In therapeutic cloning an embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment.
What are some of the hesitations of using stem cells?
The use of stem cells has potential risks such as transfer of viral infection
Some people have ethical or religious objections.
Describe some of the uses of plant stem cells from meristems.
Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.
Rare species can be cloned to protect from extinction.
Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.
What is the definition of diffusion?
Diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.
What factors affect the rate of diffusion?
Temperature
Concentration gradient
Surface area to volume ratio
(Diffusion distance)
Why do multicellular organisms require transport systems but unicellular organisms do not?
A single-celled organism has a relatively large surface area to volume ratio. This allows sufficient transport of molecules into and out of the cell, by diffusion, to meet the needs of the organism.
Multicellular organisms have a low surface-area to volume ratio so they require transport systems.
Explain how the lungs are adapted for gas exchange.
There are millions of alveoli. The alveoli increase the surface area to volume ratio of the lungs which increases the rate of diffusion.
The wall of the alveoli and the blood capillaries are one cell thick, reducing the diffusion distance
A steep concentration gradient is maintained because the wall of lungs have a very rich blood supply.
Explain how the small intestine are adapted for nutrient absorption.
There are millions of villi. The villi increase the surface area to volume ratio.
The wall of the villi are one cell thick, reducing the diffusion distance
A steep concentration gradient is maintained because the small intestines have a very rich blood supply.
What is the definition of osmosis?
Water may move across cell membranes via osmosis. Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

