growth

Question 1

define growth

Answer 1

permanent increase in the size of an organism

Question 2

define development

Answer 2

a change in form which is genetically programmed and may be modified by the environment

Question 3

what are the three stages of growth of an organism

Answer 3

cell division – increase in number of cells
cell enlargement – increase in size of cells
cell differentiation – specialisation of cells

Question 4

list 7 ways the growth of an organism can be measured in

Answer 4

changes in
length
height
wet mass
dry mass
surface area
number of leaves
circumference

Question 5

what is a growth curve

Answer 5

growth can be represented graphically with growth parameter on y axis and time on x axis

Question 6

define incomplete metamorphosis

Answer 6

a gradual change from larva to adult
larva undergoes a series of moults as it grows
each successive stage is called an instar and the insect is called a nymph
each successive nymph is larger and more like the adult although only adult has functional wings

Question 7

example of organisms which undergo incomplete metamorphosis

Answer 7

locusts
grasshoppers
cockroaches

Question 8

explain incomplete metamorphosis

Answer 8

each egg hatches into a miniature sexually immature nymph
at first the cuticle or exoskeleton is soft and flexible but soon hardens into inflexible rigid exoskeleton
hardened cuticle prevents any increase in size or length
at end of one instar exoskeleton splits open and is shed moulting revealing a soft new exoskeleton underneath
while exoskeleton is soft nymph able to increase in length
just before final instar comes to an end sexual reproductive organs complete their development and wings are almost fully formed
when final moult occurs adult insect emerges fully developed
when mating occurs and eggs are fertilised life cycle begins again

Question 9

define complete metamorphosis

Answer 9

each stage in life cycle looks completely different from every other stage and intermediate stages do not look anything like the adult
no moulting occurs
intermediate stages are not called nymphs but rather egg larva pupa adultr

Question 10

examples of complete metamorphosis

Answer 10

butterflies
houseflies
mosquitoes

Question 11

explain complete metamorphosis

Answer 11

eggs usually laid in complete warmth moisture oxygen and have access to suitable food source when they hatch
when larva emerges move around to find food
feeding in larval stage allows for rapid growth
no feeding occurs in pupal stage and undergoes rearrangement
adult emerges when pupal case splits open
adults mate and eggs are laid cycle starts again

Question 12

in a growth curve why is there a decrease in mass

Answer 12

as a result of endosperm being used up in theseed during germination

Question 13

in a growth curve why does the curve flatten out towards the end

Answer 13

seeds dispersed

Question 14

why does a plant gain mass in a growth curve

Answer 14

as green leaves develop and photosynthesis begins

Question 15

epicotyl

Answer 15

embryonic shoot above cotyledons (develops into leaves) elongates during hypogeal germination

Question 16

hypocotyl

Answer 16

region below point of attachment of cotyledons (develops into radicle) elongates during epigeal germination

Question 17

tegmen

Answer 17

inner seed coat

Question 18

what are the three things seeds need for germination

Answer 18

water
oxygen
suitable temperature

Question 19

define germination

Answer 19

development of a seed into a seedling

Question 20

define epigeal germination

Answer 20

cotyledons expand throw off testa and become photosynthetic above ground lik red bean

Question 21

define hypogeal germination

Answer 21

cotyledons remain non photosynthetic inside testa below ground like lentils

Question 22

five phases of a population growth curve

Answer 22

lag phase little growth
log phase birth rate exceeds death rate and growth is rapid
decelerating phase growth slows birth rate still exceeds death rate but by smaller margin
stationary phase birth rate equals death rate
phase of decline or death death rate exceeds birth rate

Question 23

factors which affect population size

Answer 23

predators present
poor food supply
susceptible to disease
limited space

good food supply
few predators
ability to resist disease
plenty of suitable space

Question 24

in human pop what has become less of a problem to pop growth

Answer 24

space
disease
food scarcity
no natural predators

Question 25

effects of increasing human pop growth

Answer 25

pollution exploitation of natural resources global warming extinction of animals at an abnormal and faster rate destruction of natural habitats unbalance of many ecosystems due to mans interference for pet trade control of pests and overhunting