Chapter Two: Flashcards
What is the purpose of Mitosis?
To produce Diploid Cells
What is Mitosis?
A type of cell division
When does Mitosis occur?
Whenever more cells are needed
What is the product of Mitosis?
Two new cells which are identical to each other
Name the seven phases of Mitosis:
Interphase Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis
What happens at Interphase?
The Chromosomes in the nucleus are copied.
What happens at Prophase?
The chromosomes increase
What happens at Prometaphase?
The chromosomes line up
What happens at Metaphase?
The cell begins to split
What happens at Anaphase?
The cell splits
What happens to the DNA when Chromosomes divide?
The DNA model (which is made of two strands) separate. New strands are then made for each divided strand.
What is Asexual reproduction?
Reproduction which needs only one parent
Why are the offspring of asexual reproduction identical?
As there is no mixing of genetic information
What are the offspring of asexual reproduction called?
Clones
Where does asexual reproduction occur?
Mostly in plants.
Can occur in starfish and sea anemones.
Where does growth occur in plants?
Mainly at shoot and root tips and in special growth zones like buds
Where does growth occur in animals?
New cells can be made by most tissue
How does growth occur in plants?
Size increase often caused by increasing size of cells by absorbing water in the vacuole
How does growth occur in animals?
Size increase brought about by increasing the number of cells
How do cells differentiate in plants?
Most plants can differentiate into different cell types
How do cells differentiate in animals?
Only stem cells can differentiate
What are stem cells?
Undifferentiated cells found in animals
What is a feature of stem cells?
They have the ability to grow into different tissues
Where do stem cells come from?
Human embryos or adult bone marrow
What could stem cells be used for?
- Making new brain cells
- Rebuilding bones and cartilage
- Repairing damaged immune systems
- Making replacement heart valves
What are the advantages of embryonic stem cells?
- Easy to extract from embryos
- Produce any type of cell
- Replace faulty cell with healthy cell
What are the advantages of bone marrow stem cells?
- Replace faulty cell with healthy cell
- No embryo destroyed
- If taken from person to be treated, the cell won’t be rejected
What are the disadvantage of embryonic stem cells?
- Embryo destroyed when cells removed (ethical issue)
- Body will reject cells without use of drugs
- May produce cancerous cells instead of healthy cells
What are the disadvantages of bone marrow stem cells?
- May produce cancerous cells instead of healthy cells
- Difficult to find and extract from tissue
- Produce only a few types of cells
What is Cancer?
The result of changes in cells that lead to uncontrolled cell division
Name seven parts of the brain:
Cerebral Cortex Hypothalamus Pituitary Gland Pons Medulla Oblongata Spinal Cord Cerebullum
What is the Cerebral Cortex?
The part of the brain responsible for intelligence, language, memory and consciousness.
What is the Hypothalamus?
The processing centre in the brain that controls body temperature.
What is the pituitary gland?
The gland responsible for releasing hormones (such as follicle stimulating hormone[FSH])
What is the function of FSH?
It triggers egg release and progesterone production in the ovaries.
What is the pons?
Where the spinal cord and brain meet.
What do the pons and the medulla oblongata have in common?
They both regulate breathing.
What is the medulla oblongata?
The control centre for a number of vital body functions such as heartbeat pacing, controlling blood vessels and blood pressure and setting the rate and depth of your breathing
What do the spinal cord and brain make up?
The central nervous system
What is the Cerebellum responsible for?
Co-ordinated body movements, posture and balance.
What are CT scans?
Scans that give 2D X-ray images of the body from one angle.
What are PET scans?
Scans that use radioisotope tracer drugs (etc. fluorine-18) that emit gamma rays that allow the PET scanner to produce images.
Name the five senses and their sense organ:
Touch - Skin Smell - Nose Sight - Eyes Taste - Mouth Sound - Ear
What is unique about skin in terms of senses?
It can detect two stimuli: temperature and pain.
What is a sense organ?
A part of the body that can detect a specific stimuli
What do receptors detect?
A change in environment
What is the function of sensory neurones?
To carry signals from the receptors to the CNS (central nervous system)
What is the function of relay neurones?
To carry messages from one part of the CNS to another
What is the function of motor neurones?
To carry signals from the CNS to effectors
Name the organelles of a Neuron:
Dendrites Dendron Nucleus Axon Axon Terminals
What is the function of the dendrites?
To receive impulses from receptor cells
What is the function of the Axon terminals?
Pass impulse to other neurones
What is a synapse?
A tiny gap made when two neurons meet
How do signals cross the synapse?
They use chemicals released by the neuron. The chemical diffuses across the gap and cause the next neuron to transmit an electrical signal.
What are the chemical messengers that cross the synapse called?
Neurotransmitters
What is the purpose of the reflex arc?
What controls reflex reactions.
What is the purpose of the reflex reactions?
Allows a quick response when the safety of the organism is at risk
What does the reflex arc cause?
It causes signals to be passed directly from a sensory neurone to a motor neuron (via a relay neurone)
What is the reflex arc?
The nerve pathway which makes a fast, automatic response possible. It doesn’t require any brain power.
Name 10 parts of the eye:
Ciliary Muscle Conjunctiva Cornea Fovea Iris Lens Optical Nerve Pupil Retina Suspensory Ligament
What is the Cornea?
Front part of the tough outer coat.
Name two features of the Cornea:
It is convex
It is transparent
What is the function of the Cornea?
Refracts light (bends the light as it enters the eye)
What is the Iris?
Front part of the eye. Its muscles contract and relax to later the size of the pupil.
Why is the Iris pigmented?
So light can’t pass through
What is the function of the Iris?
Controls how much light enters the pupil
What is the lens?
Disc behind the Iris that is attached by suspensory ligaments to the ciliary muscles.
Name three features of the Lens:
Transparent
Biconvex
Flexible
What is the function of the Lens?
Focuses light onto the Retina
What is the Retina?
Lining of the back of the eye, contains photoreceptor cells.
What are the two types of photoreceptor cells in the Retina?
Rods and Cones
What are the features of Rods?
Sensitive to dim light and B&W
What are the features of Cones?
Sensitive to colour
What is the fovea?
The area in the middle of the retina, contains more cones than rods.
What is the function of the Retina?
Contains light receptors
What is the Optic Nerve?
Bundle of sensory neurones at the back of the eye
What is the function of the Optic Nerve?
Carries impulses from the eye to the brain