weaknesses Flashcards
How do fossils form?
Gradual Replacement - hard parts are replaced by minerals as they decay
Casts and Impressions - organism is buried in soft material and when it hardens an imprint is left.
Preservation - a place where no decay takes place
How do the eyes make the pupil smaller?
The circular muscles contract and the radial muscles relax
How do the eyes make the pupil larger?
The radial muscles contract and the circular muscles relax
What happens in the eye so that it can see objects that are near?
The ciliary muscles contract, which slackens the suspensory ligaments. This causes the lens to go fat.
What happens in the eye so that is can see objects that are far?
The ciliary muscles relax, which allows the suspensory ligaments to pull tight. This causes the lens to go thin
What is short-sightedness called and what lens treats it?
Myopia is treated by a concave lens
What is long-sightedness called and what lens treats it?
Hyperopia is treated by a convex lens
What is the cerebral cortex responsible for?
Consciousness, intelligence, memory and language
What is the medulla responsible for?
Unconscious activities e.g. breathing and heartbeat
What is the cerebellum responsible for?
Muscle coordination
What makes up DNA (nucleotides)?
A phosphate group, a sugar and a base (ATCG)
What happens if blood glucose levels are too high?
Insulin is secreted from the pancreas, this stimulates the uptake of glucose into liver and muscle cells.
What happens if blood glucose levels are too low?
Glucagon is secreted by the pancreas which turns glycogen stored in the liver and muscle cells to be broken down into glucose.
What is the role of thyroxine?
Thyroxine regulated metabolism
How are thyroxine levels regulated?
If blood thyroxine levels are too high, TSH (the stimulating hormone released from the pituitary gland) is inhibited. This means thyroxine levels fall.
What is the role of FSH and where is it produced?
Produced in the pituitary gland, it causes an egg to mature in a follicle, and stimulates the ovaries to produce oestrogen
What is the role of Oestrogen and where is it produced?
Produced in the ovaries, causes the lining of the uterus to grow and stimulates the release of LH. It inhibits FSH.
What is the role of Progesterone and where is it produced?
Produced in the ovaries, maintains the lining of uterus. Inhibits release of LH and FSH.
What is in the contraceptive pill?
Oestrogen and Progesterone. Oestrogen inhibits FSH so an egg cannot mature. Progesterone inhibits FSH and LH so an egg cant mature OR be released.
Describe the process of a reflex reaction
- Receptor is stimulated
- Impulses travel along the sensory neurone to the CNS
- Impulses passed along a relay neurone
- Impulses travel along motor neurone
- Impulses reach effector which causes a response (e.g. muscle contracts)
Define ‘homeostasis’
The ability to maintain a constant internal set of conditions despite changes in external environments.
What indusrial use does Auxin, Gibberellin and Ethene have?
Auxin - killing weeds, tissue culture, growing plans from cuttings
Gibberellin - controlling dormancy, inducing flowering, enlarging fruit
Ethene - stimulates ripening of fruit
Explain the process of protein synthesis
- mRNA is made by copying the code of DNA
- the mRNA passes the code to ribosomes in the cytoplasm
- the correct amino acids are brought to the ribosomes in the correct order by carrier molecules
What are the 3 types of mutations?
Insertion - a new base is inserted into the DNA base sequence
Deletion - a random base is deleted from the sequence
Substitutions - a base is randomly changed to a different base
