SB1 - Key concepts in Biology Flashcards
What is a Eukaryotic cell?
A cell with a nucleus
Give some examples of Eukaryotic cells:
- Animal cells
- Plant cells
What is a Prokaryotic cell?
A cell which does not have a nucleus
—> DNA is free to roam around in the cell
Give some examples of Prokaryotic cells:
Bacteria
What sub-cellular structures do animal cells have?
- Nucleus
- Cell membrane
- Mitochondria
- Ribosomes
What sub-cellular structures do plant cells have?
- Nucleus
- Mitochondria
- Cell membrane
- Cell wall
- Vacuole
- Ribosomes
What sub-cellular structures do bacteria cells have?
- Chromosomal DNA
- Plasmid DNA
- Cell membrane
- Ribosomes
- Flagella
What is the Nucleus?
Contains genetic material which controls the cell’s activities
—> Including DNA
What are Ribosomes?
Tiny structures where protein synthesis occurs
Where are Ribosomes found?
Rough endoplasmic reticulum
What is Cytoplasm?
A jelly-like material that contains dissolved nutrients, salts and organelles
What occurs in the Cytoplasm?
Chemical reactions
What is the cell membrane?
A selectively permeable membrane surrounding the cell and controlling the entry and exit of materials
What is mitochondria?
Organelles that contains the enzymes for respiration & where most energy is released in respiration
What type of respiration occurs in mitochondria?
Aerobic
What is a Chloroplast?
Organelle that contains chlorophyll, which absorbs light energy for photosynthesis
—> Contains the enzymes needed for photosynthesis
What colour is chlorophyll?
Green
What is the role of the Cell wall?
To provide structure and protection to the cell
What are plant cell walls made out of?
Cellulose
What is a vacuole?
A space within the cytoplasm of plant cells that contains cell sap
—> Also improves cells rigidity
What is the flagella?
Long, thin ‘whip-like’ tails attached to bacteria
What’s the purpose of the flagella?
Allows bacteria to move
What are plasmids?
Small rings of DNA
What is the function of plasmids?
Codes for extra genes to those provided by chromosomal DNA
Function of chromosomal DNA?
Floats in the cytoplasm
Why does the chromosomal DNA float in the cytoplasm?
Bacterial cells have no nucleus
Cells specialise by going through which process?
Differentiation
What is Differentiation?
A process that involves the cell gaining new sub-cellular structures for it to be suited to its role
Give 3 examples of specialised cells in animals:
- Sperm cells
- Egg cells
- Ciliated epithelial cells
Give 3 examples of specialised cells in plants:
- Root hair cells
- Xylem cells
- Phloem cells
What are sperm cells?
Specialised to carry the male’s DNA to the ovum for successful reproduction
How are sperm cells adapted to aid swimming?
- Streamlined head & long tail
- Many mitochondria
How does lots of mitochondria aid sperm cells to swim?
Supplies the energy to allow the cell to move
—> Respiration occurs here
How are sperm cells adapted to fertilisation
- Acrosome
- Haploid nucleus
How does the acrosome aid sperm cells to fertilise?
Acrosome contains digestive enzymes which break down
the outer layers of membrane of the egg cell
How does the haploid nucleus aid sperm cells to fertilise?
Contains 23 chromosomes
—> Joins up with egg cell to create a zygote
How many chromosomes does a normal human body cell have?
46
What is the slime coat on bacteria for?
Protection
Does all bacteria have slime coats?
No
Only some do
What are egg cells?
Specialised to accept a single sperm cell and develop into an embryo
How are egg cells adapted to aid the process of fertilisation?
Surrounded by a special membrane
How does the special membrane aid egg cells during fertilisation?
Special membrane can only accept one sperm cell, then becomes impermeable
How are egg cells adapted to aid the development of an embryo (after fertilisation)?
- Lots of mitochondria
- Large size & Cytoplasm
How does having lots of mitochondria aid egg cells during the development of an embryo?
Provides an energy source for the developing embryo
How does having a large size and cytoplasm aid egg cells during the development of an embryo?
Allows quick, repeated division as the embryo grows
What are Ciliated epithelial cells?
Specialised to waft bacteria (trapped by mucus) to the stomach
How does having cilia aid Ciliated epithelial cells to protect our body against illnesses?
Cilia wafts bacteria trapped by sticky mucus down to the stomach, killed by the stomach acid
Which cells produce mucus?
Goblet cells
What are Root hair cells?
Specialised to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots
How are root hair cells adapted to aid osmosis?
- Large surface area
- Permanent vacuole
How does having a large surface area aid root hair cells to carry out osmosis?
More water can be taken in
How does having a permanent vacuole aid root hair cells to carry out osmosis?
Affects the speed of movement of water from the soil to the cell
How are root hair cells adapted to aid active transport?
Lots of Mitochondria
How does having mitochondria aid root hair cells to carry out active transport?
Provides energy from respiration
—> To carry out active transport of mineral ions to root hair cells
What are Xylem cells?
Specialised to transport water and mineral ions up the plant from the roots to the shoots
How are Xylem cells adapted to aid transport of water & mineral ions?
- During formation, Lignin is deposited
- Lignin is deposited in spirals
How does Lignin being deposited (during formation) aid Xylem cells to transport of water & mineral ions?
Causes cells to die
—> Becomes hollow and are joined end-to-end to form a continuous tube
—> Water & mineral ions can move through
How does Lignin being deposited in spirals aid Xylem cells to transport water?
Helps cells to withstand the pressure of the movement of water
What are Phloem cells?
Specialised to carry the products of photosynthesis (food) to all parts of the plants
Give some examples of substances transported in the phloem
- Sucrose
- Amino acids dissolved in water
How is energy supplied to the phloem cells if there aren’t any sub-cellular structures?
Its supplied by the mitochondria of the companion cells
What is a sieve tube dependant on?
The companion cells
What is translocation?
The transport of dissolved material within a plant
What does translocation require?
Energy
Describe the direction of transport in the xylem cells
Upwards from roots to leaves