Higher Biology
Revision Exercise
Unit 3
Control and Regulation
Plant Growth/Growth Patterns
1. Growth is the ___________
irreversible increase in the mass of an
organism
2. In plants growth is restricted to regions called __________.
meristems
3. ________
Primary plant growth occurs at ______
apical meristems (root and
shoot tips) where newly formed cells become elongated,
differentiated
vacuolated and ____________.
4. __________
Secondary growth occurs in a perennial plant at a _______
lateral
cambium
meristem called _________.
rings of secondary xylem
5. Cambial activity produces annual ______
and phloem. Each ring of secondary ______
xylem contains a region of
large vessels called _______
spring wood and a region of smaller
vessels called ________
autumn wood.
6. ________
Animals do not possess meristems. Instead growth occurs all
body
over a developing animal’s _____.
7. __________
Flowering plants (angiosperms) have extensive powers of
regeneration whereas mammals have only _______
limited powers.
_____________
8. Investigations into growth often involve measuring a variable
height length etc.
factor such as fresh weight, _______,
9. A graph of the results normally takes the form of a ________
sigmoid
(S-shaped) growth curve.
10. Growth ________
patterns vary from one type of organism to another.
Genetic Control
1. The characteristic features of a cell are controlled by its______.
genes
2. To prevent __________
resources being wasted, some genes can be
switched on and off as required.
3. The operon (______________)
Jacob-Monod
hypothesis states that a
operator gene is
structural gene remains switched off while its ________
repressor from a regulator gene. The
combined with a __________
structural gene becomes switched on and codes for its protein
inducer prevents the repressor combining with the
when an ________
operator gene.
4. All the chemical processes that occur in a living organism are
metabolism
known collectively as its ___________.
5. Each stage in a metabolic _________
pathway is controlled by an
enzyme.
6. Production of each ________
enzyme is controlled by a particular gene
(or group of genes).
7. A ________
mutated gene is unable to code the information needed to
produce its enzyme. Lack of this enzyme may lead to an inborn
error
PKU
_____ of metabolism such as _____.
8. During ____________,
differentiation cells become specialised to perform
functions
specific _________.
9. Within a differentiated cell, only certain genes continue to
operate and the other genes are switched _____.
off
________
10. In some cases genes that were switched off can be switched
on
reversal of differentiation.
___ again bringing about a ________
11. Two categories of genes exist: the genes that code for vital
metabolites (and are switched on in all cells); the genes that
___________
proteins characteristic of a particular type of cell ( and
code for ________
cell
are switched on only in that type of _____.
Hormonal influences on growth
1. The pituitary gland produces both ______________
growth hormone (which
thyroid stimulating hormone
promotes human growth) and _______________________
(TSH).
2. The ______
thyroid gland responds to TSH by producing ________
thyroxine
which controls metabolic processes.
3. The auxins make up a group of plant growth substances
auxin is called indole acetic
(hormones). The most common ______
IAA
acid (____).
4. IAA is produced in root and shoot tips and promotes cell
division cell _________
elongation and differentiation of cells.
________,
5. Low concentrations of auxin which stimulate ____
root elongation
Higher concentrations of auxin which
have little effect on shoots. ______
inhibit root elongation.
stimulate shoot elongation ______
6. Unequal distribution of auxin causes shoots to _____
bend
phototropic movements.
producing __________
7. Apical buds exert apical __________
dominance by producing high
lateral buds.
concentrations of auxin which inhibit growth of ______
8. Auxin prevents leaf and fruit _________
abscission and promotes fruit
formation.
9. Synthetic auxins act as _________
herbicides by disrupting growth of
weeds more than grass-like plants which absorb
broad-leaved ______
narrow leaves.
less through their ______
10. Synthetic auxins stimulate formation of __________
adventitious roots on
stem cuttings.
11. The __________
gibberellins make up a second group of plant growth
substances. The most common gibberellin is called
gibberellic acid (GA).
_____________
12. GA promotes cell division and elongation in _______.
stems
13. GA reverses genetic ________
dwarfism by promoting stem ________
internode
elongation.
14. GA induces production of _________
a-amylase in cereal grains and
dormancy in winter buds.
breaks ________
Physiological Homeostasis
1. Nitrogen, __________,
phosphorus potassium and __________
magnesium are four
macro-elements needed by plants for healthy growth.
2. A plant grown in a water culture experiment lacking one
essential macro-element displays certain deficiency
________ symptoms.
3. _____
Lead inhibits the action of certain enzymes, It is poisonous to
intelligence of
humans and may have a detrimental effect on the __________
children.
4. Iron is essential to humans for the formation of ___________.
haemoglobin
5. ________
Calcium is essential to humans for the formation of healthy
teeth
bones and _____.
6. _________
Vitamin D is needed to promote the uptake of calcium ions by
rickets
bone and prevent ______.
7. Drugs such as _______,
nicotine alcohol and __________
thalidomide harm a
foetus
developing human ______.
8. A plant grown in darkness develops a weak ____
long stem and
etiolated
small curled leaves and is said to be ________.
9. Green plants show positive ____________
phototropism by growing
light from one direction.
towards a source of _____
10. In order to flower, long day plants require a number of hours of
above a critical level. Short day plants need a critical
light ______
darkness Such a response by an organism
number of hours of ________.
photoperiodism
to a photoperiod of a certain length is called _____________.
11. Seasonal gonadal activity in many birds and mammals is
photoperiods of a certain length.
stimulated by the arrival of daily ___________
12. Small mammals with short gestation periods tend to be ____
long
day breeders. Large mammals with long gestation periods tend to
short day breeders.
be _____
13. Breeding is timed so that the young are born in ______
spring when
the conditions are favourable.
Homeostasis/Populations/Succession
1. To function efficiently, many aspects of the human body’s
internal
limits
______ environment must be maintained within tolerable _____.
2. Physiological ___________
homeostasis is the name given to this
maintenance of the internal environment despite changes in the
external
_______ environment.
3. Homeostasis operates on the principle of ________
negative feedback
control. By this means a change in the internal environment is
receptors which send messages to ________.
effectors
detected by _________
These trigger responses which negate the deviation from the
set point
norm and return the internal environment to its _________.
4. Population ________
dynamics is the study of population changes and
the factors which cause them.
5. A population increases until it reaches the _______
carrying capacity of
stable
the environment and then it remains relatively ______.
6. A _________
population is prevented from increasing in size indefinitely by
resistance
several factors known collectively as environmental _________.
7. Some of these factors affect the growth of the population in a
independent of population density. Other factors operate
manner ___________
density-dependent manner.
in a _______________
8. In a natural ecosystem, a population is kept relatively stable by
feedback control
density-dependent factors effecting negative _________
(homeostasis).
9. The population numbers of many wild plants and animals are
monitored by humans.
__________
10. This provides data which helps humans to manage species
food to control ____
pest species, to assess pollution levels
used for _____,
indicator species and to protect and ___________
conserve
using ________
endangered species.
11. The change which involves a regular progression from a
pioneer community of plants to a climax community is called
_______
succession
__________.
12. During succession each community enjoys a period of shortmodifies the habitat. In doing
term stability during which time it ________
favourable to itself and more
so it makes the habitat less __________
favourable to its seccessor.
13. The ______
climax community is the final product of succession
climatic factors. It enjoys
whose nature is determined by soil and _______
replaced by another community.
stability and is not ________
14. Compared with a pioneer community, a climax community
biomass
possesses a more diverse range of species, a higher ________
webs
and a more complex set of food _____.