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.
What is the definition of active transport?
Give two examples of uses of active transport.
Active transport moves substances from an area of low concentration to an area of high concentration, against a concentration gradient, using energy from respiration.
Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth.
It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration.
What is the difference between a cell, a tissue, an organ and an organ system?
Cells are the basic building blocks of all living organisms.
A tissue is a group of identical cells with a similar structure and function.
Organs are aggregations of different tissues performing specific functions.
Organs are organised into organ systems, which work together to form organisms.
Where is amylase made?
Salivary glands, mouth
Pancreas
Small intestine
Where is lipase made?
Pancreas
Small intestine
Where is protease made?
Stomach
Pancreas
Small intestine
What does lipase do?
Lipase breaks down lipids into 3x fatty acids and glycerol
Lipid —> Fatty acids x3 + Glycerol
What do proteases do?
Proteases break down protein into amino acids
What do carbohydrases do?
Carbohydrases break down carbohydrates to simple sugars.
What does amylase do?
Amylase is a carbohydrase which breaks down starch.
Where are all 3 types of digestive enzymes made?
All 3x are made in the Small intestine and Pancreas
Stomach also makes protease
Mouth also makes amylase
What is the role of bile in digestion?
It is alkaline to neutralise hydrochloric acid from the stomach.
It also emulsifies fat: breaks down large lipid droplets into small lipid droplets which increases the surface area:volume ratio. This is to help lipase work faster.
The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.
Where is bile made and stored?
Bile is made in the liver and stored in the gall bladder.
The heart is an organ that pumps blood around the body in a double circulatory system. What does this mean?
Two circuits:
heart —> lungs —> heart
heart —> body —> heart