Biology Paper 1 Flashcards
What are the differences between a prokaryote and a eukaryote?
Prokaryotes do not contain a nucleus, whereas eukaryotes do. Prokaryotes have a cell wall, whereas eukaryotes do not.
Name the 5 common features of a plant and animal cell.
Cell membrane, cytoplasm, nucleus, mitochondria, ribosomes.
State the 3 features structures that a plant cell contains and an animal cell does not.
Chloroplasts, cell wall, vacuole.
What is the function of the nucleus?
Contains genetic material and controls the activities of the cell.
What is the function of the cell membrane?
To control the substances that move in and out of the cell.
What is the function of the cytoplasm?
Contains all the organelles and is the site of many chemical reactions.
What is the function of the mitochondria?
The site of respiration where energy is released.
What is the function of the ribosomes?
The site of protein synthesis, where new proteins are made.
What is the function of the permanent vacuole?
It contains cell sap and enzymes. It can also store excess water.
What is the function of a chloroplast?
It is filled with chlorophyll, absorbs light and is where photosynthesis happens.
What material makes up cell walls in plants?
Cellulose.
State why prokaryotes do not contain membrane bound organelles.
Membrane bound organelles are too large to fit in a prokaryote.
What is a specialised cell?
A cell that has specific features or adaptations to perform a particular job.
Describe how a sperm cell is adapted.
Tail/flagellum - for locomotion/movement
Acrosome - to digest the egg surace
Many mitochondria - for respiration to release energy to swim to the egg
Describe how a muscle cell is adapted.
Many mitochondria for respiration to release energy to the muscle for contraction.
Describe how a root hair is adapted.
Hairs/projections - to increase the surface area to absorb more water/nutrients.
No chloroplasts - not needed to photosynthesise.
Describe how a nerve cell is adapted.
Long axon - to carry messages long distances
Many dendrites to make any connections
Describe how a xylem cell is adapted.
Dead, hollow cells that form a tube.
Lignin for strength and to withstand water pressure.
Describe how a phloem cell is adapted.
Live cell, contains sieve plates to distribute sugar evenly throughout the plant.
Describe how a red blood cell is adapted.
No nucleus and a biconcave dip to carry more haemoglobin which binds to oxygen.
What is cell differentiation?
When a cell becomes a specialised cell
When do most cells differentiate in an animal?
Foetal stage
When do most cells differentiate in a plant?
They can differentiate at any times
In mature animals what is cell differentation used for?
Repair of damaged tissues or cells
Name 2 types of microscopes
Light/optical microscope
Electron microscope
State 2 advantages and disadvantages of a light/optical microscope
Advantages: Portable, easy to use, see colour, inexpensive, live specimens Disadvantages - 2D, low resolution, low magnification
State 2 advantages and disadvantages of an electron microscope
Advantages: 3D images, high magnification, high resolution Disadvantages - Expensive, black and white images only, specimen must be dead
What is meant by resolution or resolving power?
The fineness of detail that can be seen in an image. The higher the resolution of an image, the more detail it holds. The ability to distinguish between 2 points.
What is an order of magnitude?
A number to the base of 10, often used to make comparisons.
How do you calculate magnification?
Magnification = Image size / Actual size
How do you rearrange the equation to calculate the actual size of an image?
Actual size = Image size / Magnification
What is 1260000nm as standard form?
1.26 x 10-3m
What is 0.0000001m as standard form?
1 x 10 -7m
What is a stage micrometre?
A glass slide with a scale on it used to calibrate the eyepiece
What is a graticule?
A glass or plastic disc fitted into the eyepiece of a microscope used to estimate the size of a specimen
How do you rearrange the equation to calculate the image size?
Image size = Magnification x Actual size
What are genes?
A section of DNA that codes for a particular protein
In what arrangement do we usually find chromosomes?
In pairs
How many chromosomes does a human adult have?
46 or 23 pairs
What happens to the cell before it divides?
The nucleus disappears, chromosomes become short, fat and they double.
What is produced during mitosis?
Genetically identical daughter cells
What is produced during meiosis?
Gametes
What type of cell division can be called “double division”?
Meiosis
Why is mitosis important?
Growth, repair and maintaining the chromosomes number
What do we call a cell with 2 sets of chromosomes?
Diploid
What do we call a cell with 1 set of chromosomes?
Haploid
What type of cell is produced during meiosis in males and females?
Male - sperm
Female - egg
If a cell with a diploid number 24 undergoes meiosis, how many chromosomes would be in each daughter cell?
12
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration, down a concentration gradient.
What is osmosis?
The movement of water particles from a dilute solution to a more concentrated solution, through a partially permeable membrane
What is active transport?
The movement of particles against a concentration gradient, from a low concentration to a high concentration requiring energy.
State 3 substances that can move by diffusion in animal cells.
Oxygen, carbon dioxide and glucose
How can we increase the rate of diffusion?
Increase the concentration gradient, decrease the diffusion distance/thickness of surface, increase the surface area
How is a root hair cell adapted for osmosis?
Lots of hairs/projections that increase the
surface area so more water can be absorbed
How are cells in the small intestine adapted for active transport?
Many mitochondria to release
energy for active transport
What is required for active transport?
Energy
What is a concentration gradient?
The difference between two concentrations