Quick Review Flashcards - Click to flip and test your knowledge!
Question
What term refers to the chemical compounds produced by plants to coordinate growth and respond to stimuli?
Answer
Phytohormones (plant hormones)
Question
Who were the first scientists to use the term 'hormone' in 1902?
Answer
William Bayliss and Ernest Starling
Question
The Greek word 'phyton', which forms part of the term 'phytohormone', means _____.
Answer
Plant
Question
In which specific areas of a plant does cell division primarily occur?
Answer
Meristems
Question
Where are meristems typically located in a plant body?
Answer
Just behind the tips of shoots or roots
Question
Which scientist coined the term 'Auxin' in 1928?
Answer
F.W. Went
Question
What is the literal meaning of the Greek word 'auxein'?
Answer
To grow
Question
What is the full name of the natural auxin $IAA$?
Answer
Indole 3-acetic acid
Question
In higher plants, where are auxins most concentrated?
Answer
Actively growing regions like shoot and root apices
Question
How do auxins physically affect the cell wall during elongation?
Answer
They induce cell wall loosening or relaxation
Question
How does the rate of cell elongation relate to auxin concentration?
Answer
It is directly proportional
Question
Which plant hormone is primarily responsible for delaying leaf senescence?
Answer
Auxins
Question
What phenomenon occurs when apical buds inhibit the growth of lateral buds?
Answer
Apical dominance
Question
Removing apical buds allows lateral buds to grow; which hormone is being removed to cause this?
Answer
Auxins
Question
Which hormone can be applied to cuttings of plants like roses to induce rooting?
Answer
Auxins
Question
What is the term for the development of fruits without fertilisation?
Answer
Parthenocarpy
Question
Which specific form of gibberellic acid is the most widely studied?
Answer
$GA_{3}$
Question
What is the primary function of gibberellins regarding stem structure?
Answer
Promoting internode elongation
Question
How do gibberellins affect seed dormancy?
Answer
They break dormancy to initiate germination
Question
Which industry uses gibberellic acid to accelerate the malting process?
Answer
The brewing industry
Question
Gibberellins are used in horticulture to enhance the longitudinal growth of which types of plants?
Answer
Dwarf plants
Question
Who discovered cytokinins in the 1950s?
Answer
Skoog and Miller
Question
Unlike auxins which promote cell elongation, cytokinins primarily stimulate cell _____.
Answer
Division
Question
Where are cytokinins primarily synthesised within a plant?
Answer
Root tips
Question
Which plant hormone acts against auxins by inhibiting apical dominance?
Answer
Cytokinins
Question
Cytokinins delay senescence by promoting the synthesis of which pigment?
Answer
Chlorophyll
Question
Which hormone is unique for being a gas at ordinary temperatures?
Answer
Ethylene
Question
Who identified the gas emanating from oranges that ripened bananas as ethylene?
Answer
R. Gane
Question
Where is ethylene produced in higher plants?
Answer
In all living cells (especially meristematic tissues and ripening fruits)
Question
Which hormone is used to induce flowering in mango plants?
Answer
Ethylene
Question
What is the effect of ethylene on the sprouting of potato tubers?
Answer
It initiates or promotes sprouting
Question
How does ethylene affect the rate of senescence in plants?
Answer
It accelerates it
Question
What is the primary growth-retarding hormone in plants?
Answer
Abscisic acid (ABA)
Question
In which cellular organelle is Abscisic acid found?
Answer
Chloroplasts
Question
Why is Abscisic acid often referred to as the 'stress hormone'?
Answer
It increases plant tolerance to various kinds of stresses
Question
What effect does ABA have on stomata during water stress?
Answer
It stimulates the closure of stomata
Question
How does ABA affect seed germination?
Answer
It inhibits germination (induces dormancy)
Question
What is the term for the shedding of leaves, flowers, and fruits, which is accelerated by ABA?
Answer
Abscission
Question
What is the general term for growth movements in response to unidirectional external stimuli?
Answer
Tropic movements (tropism)
Question
From which Greek word is the term 'tropism' derived, and what does it mean?
Answer
'tropos', meaning 'to turn'
Question
What is the definition of phototropism?
Answer
Movement or growth in response to light
Question
Which part of the plant is typically positively phototropic?
Answer
The shoot
Question
Which part of the plant is typically negatively phototropic?
Answer
The root
Question
During phototropism, on which side of the shoot do auxins accumulate?
Answer
The shaded side (not facing the light)
Question
What causes a plant shoot to bend towards a light source?
Answer
Rapid cell elongation on the shaded side due to auxin accumulation
Question
What is the term for plant growth in response to the Earth's gravity?
Answer
Geotropism (or gravitropism)
Question
How do roots typically respond to gravity?
Answer
They are positively geotropic (grow downwards)
Question
How do shoots typically respond to gravity?
Answer
They are negatively geotropic (grow upwards)
Question
Which laboratory instrument is used to demonstrate geotropism by rotating a plant to eliminate the unidirectional effect of gravity?
Answer
Clinostat
Question
What is the definition of hydrotropism?
Answer
The movement of plant parts in response to water or moisture
Question
Between gravity and moisture, which is a more effective stimulus for root direction?
Answer
Moisture (water)
Question
What is the movement of plant parts in response to touch stimuli called?
Answer
Thigmotropism
Question
Which structures in climbing plants like sweet peas show thigmotropic responses by coiling around supports?
Answer
Tendrils
Question
What is the definition of chemotropism?
Answer
The growth or movement of plant organs in response to chemicals
Question
The growth of a pollen tube towards an ovule is an example of which tropism?
Answer
Chemotropism
Question
What chemicals typically secrete from the female gametophyte to attract the pollen tube?
Answer
Sugars and peptones
Question
What is heliotropism?
Answer
The phenomenon of flowers (like sunflowers) following the sun's path
Question
How do auxins facilitate heliotropism in sunflowers?
Answer
They migrate to the shaded side, causing the stem to bend the flower towards the sun
Question
Which hormone is used commercially to increase the size of grapes and improve their shape?
Answer
Gibberellins
Question
What is the main site of synthesis for auxins?
Answer
Shoot apical meristems and young leaves