Final Final Revision Flashcards
What are the main organelles found in a cell?
Cell wall, vacuole, cell membrane, cytoplasm, chloroplast, nucleus, mitochondria
These organelles perform essential functions within the cell.
What is the function of the cell wall?
Provides rigidity and structure to the cell
What does the vacuole store?
Water, nutrients, and solutes
It is responsible for cell turgidity.
What is the role of the cell membrane?
Regulates what enters and exits the cell
What is cytoplasm?
A jelly-like substance that suspends organelles
What is the primary function of chloroplasts?
Sites of photosynthesis
What does the nucleus contain?
DNA and nucleolus
It is the main structure for genetic information.
Where does cellular respiration occur?
Mitochondria
What are plasmodesmata?
Pores in the cell wall that connect adjoining cells
What is the shoot apical meristem?
A region of actively dividing cells at the top of the stem
What does ‘apical’ refer to in the context of meristem?
The top or main growing point
What type of growth is provided by the apical meristem?
Primary growth, which is upward growth
What characterizes the cells in the apical meristem?
Small, densely packed, actively dividing cells
What happens in the zone of differentiation?
Cells begin to take on specific roles within the stem
What do axillary buds provide?
Lateral growth
What hormone promotes cell elongation?
Auxin
It is produced in young leaves and the apical meristem.
What happens when the apical meristem is removed?
Cytokinins become more dominant, promoting lateral growth
What is apical dominance?
The phenomenon where the apical meristem inhibits the growth of axillary buds
What effect does high light intensity have on plant growth?
Promotes auxin production, leading to more upward growth
What hormone is produced in low light levels?
Gibberellic acid
It promotes stem elongation and can lead to leggy plants.
What is etiolation?
The condition of plants growing long and spindly due to low light
What is the role of gibberellins in high temperatures?
Increase stem elongation and faster cell division
What is vernalization?
The process by which a period of cold initiates flowering
What is the difference between monocot and dicot stems?
Monocot stems have vascular bundles randomly arranged; dicot stems have them arranged in a circle
What is the function of xylem?
Moves water and nutrients from the roots to the leaves
What does phloem transport?
Products of photosynthesis and nutrients in any direction around the plant
What is secondary thickening?
The process where vascular cambium produces secondary xylem and phloem, thickening the stem
What is the role of vascular cambium in plant growth?
Vascular cambium joins neighboring vascular bundles to create a continuous ring of cambium that can actively divide.
What happens during the second year of plant growth involving vascular cambium?
The vascular cambium produces secondary xylem on the inside and secondary phloem on the outside, leading to secondary thickening or growth.
What is the function of the cork cambium?
Cork cambium produces new cork cells that form a protective, water-resistant layer around the stem.
What occurs if new cork is not produced during secondary thickening?
The epidermis would crack and burst open, exposing internal structures.
What are the collective terms for the female and male parts of a flower?
Pistil for female parts and stamen for male parts.
What is the function of the anther in a flower?
The anther produces pollen.
What role does the stigma play during fertilization?
The stigma receives pollen during the fertilization process.
Fill in the blank: The ovary develops into the _______.
fruit
What is the process of vernalization?
A cold period that initiates flower formation by changing apical meristem buds from leaf buds to flowering buds.
How does photoperiodism affect flowering in plants?
Different lengths of light exposure can either suppress or promote flower bud initiation.
What occurs when pollen lands on the stigma?
The pollen germinates and grows a pollen tube down through the style.
What is double fertilization in plants?
A process where one male gamete fertilizes the egg to form the zygote, and the other fertilizes two polar nuclei to form the endosperm.
What does the zygote develop into after fertilization?
The zygote develops into the embryo.
What is the function of the endosperm?
The endosperm serves as a food resource for the developing seed.
What are the three main structures that develop from the embryo?
- Plumule (shoot) * Epicotyl * Radical (root)
What is the difference between endospermic and non-endospermic seeds?
- Endospermic seeds retain endosperm as storage tissue * Non-endospermic seeds use endosperm to develop fleshy cotyledons
What is innate dormancy in seeds?
Dormancy that is under genetic control, often diminishing after the seeds are shed from the plant.
Fill in the blank: After ripening is the process where seeds can germinate after a period of _______.
detachment
What is hard seededness?
A condition where seeds have impermeable testa that prevent germination.
What causes induced or enforced dormancy in seeds?
Lack of specific environmental conditions such as water, oxygen, light, or suitable temperature.
What is the primary root or embryonic root called?
Radical
What is the transitional structure between the root and stem called?
Hypocotyl
What is the term for the embryonic shoot or leaves?
Plumule
What is enforced dormancy in seeds?
Enforced dormancy occurs when seeds cannot germinate due to unfavorable environmental conditions such as lack of water, oxygen, light, or unsuitable temperatures.
These conditions prevent the activation of metabolic pathways necessary for germination.
What triggers induced dormancy?
Induced dormancy, also known as secondary dormancy, occurs when seeds have met the conditions for innate and enforced dormancy but still do not germinate.
This type of dormancy can be difficult to break even under favorable conditions.
What are the three types of dormancy in seeds?
- Innate dormancy
- Enforced dormancy
- Induced dormancy
What are natural processes that can break seed dormancy?
- Abrasion by soil
- Fire
- Freezing
- Leaching of inhibitors
- Digestive acids
- Bacteria
- Soil disturbance
What are some human-induced methods to break seed dormancy?
- Scarification
- Heat treatment
- Stratification (cold and warm periods)
- Soaking in water
- Acid treatment
What is the first step in the process of germination?
Water imbibition, where the seed coat softens to allow water into the seed.
The seed coat must be soft enough for water to enter through the micropyle.
What hormone is produced after water enters the seed during germination?
Gibberellic acid.
This hormone is crucial for initiating the germination process.
What enzyme is produced when gibberellic acid reacts with the aleurone layer?
Alpha amylase.
What does alpha amylase do during germination?
Breaks down starch in the endosperm into sugar, which is then absorbed by the cotyledon or scutellum.
This sugar is used for respiration and powers cell division.
What is the role of respiration in seed germination?
Respiration releases energy that powers cell division and growth of the embryo.
What are the main storage compounds in non-endospermic seeds?
- Starches
- Oils
- Proteins
What enzymes are involved in breaking down storage compounds in non-endospermic seeds?
- Amylases (starches)
- Lipases (oils)
- Proteases (proteins)
What is the difference between epigeal and hypogeal germination?
Epigeal germination: cotyledons emerge above the soil; Hypogeal germination: cotyledons remain below the soil.
Fill in the blank: In epigeal germination, the cotyledons are _______.
[above the soil]
Fill in the blank: In hypogeal germination, the cotyledons are _______.
[below the soil]
