B1: Key Concepts In Biology Flashcards
Are animals and plant cells prokaryotes or eucaryotes?
Eucaryotes
Are bacteria cells eukaryotes or prokaryotes?
Prokaryotes
What type of cells are multicellular organisms?
Animal and plant cells have
What type of cells are unicellular organisms?
Bacteria cells
Name 5 sub cellular structures that are in Both an8mal and plant cells?
Cell membrane
Nucleus
Cytoplasm
Mitochondria
Ribosome
Name the 3 sub cellular structures that are in a plant cell but not an animal cell?
Cell wall
Permanent vacuole
Chloroplasts
Name the 7 sub cellular structures in a bacterial cell?
Cell wall
Cell membrane
Plasmids
Cytoplasm
Ribosome
Nucleoid
Flagellum
What is the function of a cell membrane?
Controls which substances can pass in and out of a cell
What is the function of a nucleus?
Contains the genetic material (DNA) and controls the functions of the cell
What is the function of cytoplasm?
It is where the chemical reactions take place
What is the function of mitochondria ?
Provides cells with the energy they need to function through aerobic respiration.
What is the function of the ribosomes ?
It is the site of protein synthesis
What is the function of a cell wall?
It is made of cellulose which is a very strong substance which gives the cell strength in structure.
What is the function of the permanent vacuole?
It contains the cell sap (mixture of sugars and salts)
What is the function of the Chloroplasts ?
It is the site of photosynthesis so it produces the sugars needed for the cell
What is the function of the nucleiod?
Contains the genes that the cell needs to survive +reproduce
What is the function of the plasmids?
It has extra genes (DNA) that is different to the nucleiod DNA
What is the function of the flagellum?
To propel the bacteria
How is the genetic information in a eukaryotic cell stored?
Within the nucleus arranged in chromosomes
Describe the structure of the cytoplasm?
Fluid component of the cell which contains organelles, enzymes and nutrients
When looking at chloroplasts under a light microscope why do they appear green?
They contain chlorophyll which is a green pigment
What is the prokaryotic cell wall made of ?
Peptidoglycan
What is a haploid cell?
A cell that contains a single copy of each chromosome (half the number of chromosomes).
e.g 23 chromosomes in humans
What is a diploid cell?
A cell that contains 2 copies of each chromosome ( a full set of chromosomes)
e.g 46 chromosomes in humans
What are gametes?
Reproductive cells ( they are haploid cells)
Explain sexual reproduction in terms of chromosome number ?
2 haploid gametes fuse resulting in an embryo that has 2 chromosomes for each gene and 2 copies of each allele
How are egg cells adapted for their function?
Cytoplasm contains nutrients for the developing embryo.
Cell membrane hardens after fertilisation to prevent any other sperm entering the egg
How are sperm cells adapted to their function ?
Tail enables movement.
Acrosome contains enzymes that digest the egg cell membrane
Where are ciliates epithelial cells found?
Found in the lining of structures such as the respiratory tract or the uterus.
Describe the function of ciliated epithelial cells lining the airway?
Move in synchronised waves to move mucus up to the back of the throat so it can be swallowed
What is magnification?
The number of times bigger an image appears compared to the size of the object
What is resolution?
The smallest distance between 2 objects that can be distinguished
How does a light microscope work?
Passes a beam of light through a specimen which travels through the eyepiece lens allowing the specimen to be observed
What are 4 advantages of a light microscope ?
Inexpensive
Easy to use
Portable
Observe both dead and living specimens
What are the disadvantages of a light microscope ?
Limited resolution
How does an electron microscope work?
It uses a beam of electrons which are focused using magnets. The electrons hit a fluorescent screen which emits visible light, producing an image.
Name the two types of electron microscope?
Transmission electron microscope (TEM)
Scanning electron microscope (SEM)
What are the advantages of electron microscopes?
Greater magnification and resolution
Why do electron microscopes have a greater magnification and resolution?
They use a beam of electrons which has a shorter wavelength than protons of light
How have electron microscopes enabled scientists to develop their understanding of cells?
• Allow small sub-cellular structures (e.g. mitochondria, ribosomes) to be observed in detail
• Enable scientists to develop more accurate explanations about how cell structure relates to function
What are the 4 disadvantages of electron microscopes?
Expensive
Not portable
Require training to use it
Only dead specimens can be observed
What are enzymes ?
Biological catalysts that increase the rate of a chemical reaction without being permanently altered themselves
What is an advantage of enzymes in the body ?
They enable cellular reactions to take place at lower temperatures
What is the active site of an enzyme ?
The region of an enzyme to which a substrate molecule binds and the reaction takes place
Describe the 4 stages of a lock and key model ?
- Substrate collides with the active site of an enzyme
- Substrate binds, enzyme-substrate complex forms
- Substrate converted to products
- Products released from the active site which is now free to bind to another substrate
What factors affect the rate of an enzyme controlled reaction?
Temperature
PH
substrate concentration
Explain how increasing temperature initially affects the rate of an enzyme controlled reaction ?
• As temperature increases molecules have more KE
• Movement of molecules increases
• More enzyme-substrate complexes form
• Rate of reaction increases
Explain how increasing temperature above the optimum affects the rate of an enzyme controlled reaction?
• bonds break in the enzyme’s structure
• Active site changes shape, enzyme is denatured
• No more enzyme-substrate complexes can form
• Rate of reaction decreases
Explain how pH affects the rate of an enzyme controlled reaction?
• Enzymes have an optimum pH
• Bonds in the enzyme’s structure are altered
• Active site changes shape, enzyme is denatured
• Rate of reaction decreases
Why must large organic molecules be broken down into smaller, simpler molecules in the body?
• Large molecules are too big to be absorbed across the surface of the gut wall
• large molecules are broken down into smaller molecules for absorption into the bloodstream
What type of molecules are proteins and carbohydrates?
Polymers
What are the monomers of carbohydrates?
Simple sugar
Which group of enzymes catalyses the breakdown of carbohydrates?
Carbohydrases
Which type of carbohydrase catalyses the breakdown of starch?
Amylase
What are the monomers of protein ?
Amino acids
Which type of enzyme catalyses the breakdown of proteins?
Proteases
What is the function of lipases?
Enzymes which catalyse the breakdown of lipids into fatty acids and glycerol
Why are small molecules synthesised into larger organic molecules in the body?
Large molecules are used for storage (e.g. glycogen) or are used to build structures.
Which enzyme catalyses the formation of glycogen from glucose?
Glycogen synthase
How can the amount of energy contained in food be measured?
Measured using calorimetry
What is calorimetry?
A method of measuring the heat transfer during a chemical reaction
Describe the 7 method used to measure the amount of energy in a sample of food ?
- Add a set volume of water to a boiling tube, record initial temperature
- Record the mass of a small sample of food (e.g. bean)
- Stick the sample onto a mounted needle
- Using a bunsen burner light the food sample
- Hold the sample under the boiling tube until it burns up
- Record the maximum temperature reached by the water
- Record the final mass of the food sample
What is simple diffusion?
The net movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient
What molecules enter and leave cells via simple diffusion through the cell membrane?
Small molecules e.g. oxygen, water, glucose, amino acids
What factors affect the rate of diffusion?
• Temperature
• Concentration gradient
• Surface area of cell membrane
Define osmosis?
The net movement of water molecules from an area of high water concentration to an area of low water concentration through a partially permeable membrane
What is active transport?
The movement of molecules across a cell membrane from an area of low concentration to an area of high concentration, against the concentration gradient, using energy
