Plant growth & structure
what are the three major organs that make up the plant body
stems, leaves and roots
Which growth-promoting hormone promotes cell elongation and shoot elongation and inhibits lateral bud development?
auxin
Which vascular tissue transports water and dissolved minerals through the plant?
xylem
What are the two main sources from which plants obtain the raw materials needed for photosynthesis?
CO₂ from the atmosphere and water/mineral nutrients primarily from the soil.
In alternation of generations, which generation is diploid and produces spores?
Sporophyte
what type of meristem is responsible for primary growth and what does primary growth do
The apical meristems (SAM and RAM) are responsible for primary growth, which increases the length/elongation of plant organs.
Which hormone promotes cell division and lateral bud development while inhibiting leaf senescence?
cytokinins
What is the movement of water across a selectively permeable membrane in response to differences in solute concentration called?
osmosis
What is the difference between a macronutrient and a micronutrient?
Macronutrients are required in amounts of at least 1 g/kg of plant dry mass, while micronutrients are required in amounts of 0.1 g/kg or less.
What is the difference between the sporophyte and gametophyte generations in terms of chromosome number and what they produce?
he sporophyte is diploid (2N) and produces haploid spores by meiosis. The gametophyte is haploid (1N) and produces gametes by mitosis
A plant stem has vascular bundles arranged in a ring and contains both a pith and cortex. Is this most likely a monocot or eudicot? Explain.
Eudicot stems have vascular bundles arranged in a ring and have a pith and cortex. Monocot vascular bundles are scattered and lack both a pith and cortex.
During seed germination, an embryo produces a hormone that causes cells in the aleurone layer to produce alpha-amylase. What hormone is this, and why is alpha-amylase important?
Alpha-amylase breaks down stored endosperm into glucose, which the embryo can use for respiration and ATP production.
Put these structures in the correct order for the movement of water from the soil to the atmosphere: leaf xylem, root cortex, atmosphere, root xylem, root epidermis, stem xylem, endodermis, mesophyll.
Soil → root epidermis → root cortex → endodermis → root xylem → stem xylem → leaf xylem → mesophyll → atmosphere
Which mineral nutrient is a component of chlorophyll and also functions as an enzyme activator?
Magnesium (Mg)
What structure is the female gametophyte of an angiosperm, and how many nuclei and cells does it contain?
The embryo sac. It contains 8 nuclei but only 7 cells
A plant is increasing in diameter rather than length. Which type of growth is occurring, which meristems are responsible, and what tissues are being produced?
Secondary growth is occurring. It is caused by the lateral meristems—the vascular cambium and cork cambium—and produces secondary tissues.
A seed has absorbed water, but its germination is being inhibited. Which hormone could be responsible, and what two effects of this hormone would directly oppose the processes needed for germination?
Abscisic acid (ABA). It inhibits alpha-amylase production and promotes dormancy/storage-related processes, preventing the breakdown of food reserves needed for germination.
Explain how transpiration can move water from the roots to the leaves even though the plant does not expend ATP to directly pump the water upward.
Water evaporates from the leaf, creating tension/pull. Because water molecules exhibit cohesion, the water column remains connected. Adhesion to cell walls also helps maintain the column. This creates a transpiration stream that pulls water upward through the xylem.
A plant has a deficiency in nitrogen. Based on the notes, name three major biological molecules/processes that could be affected because of nitrogen's role.
Nitrogen is a component of proteins, nucleic acids, and chlorophyll, so all three could be affected.
During double fertilization, one sperm fuses with the egg and the other sperm fuses with the two polar nuclei. What are the chromosome numbers of the two resulting products?
Egg + sperm → 2N zygote
Sperm + two polar nuclei → 3N primary endosperm cell
A researcher discovers a plant organ that has elongated but has not increased substantially in diameter. Which type of growth occurred, which meristems were involved, and which tissues would you expect to have been produced?
Primary growth occurred. The root and/or shoot apical meristems (RAM/SAM) were responsible, producing primary tissues such as primary xylem, primary phloem, epidermis, parenchyma, collenchyma, and sclerenchyma.
Compare the effects of gibberellins and abscisic acid on a germinating seed. Explain how these hormones have opposing effects on the availability of stored food.
Gibberellins promote germination by causing the aleurone layer to produce alpha-amylase, which breaks down endosperm into glucose for the embryo. ABA inhibits alpha-amylase production and is associated with dormancy and storage of carbohydrates, thereby opposing germination.
A plant's stomata open during the day. Explain the sequence of events involving K⁺, water, guard-cell turgor, and the stomatal pore.
Guard cells pump K⁺ in, increasing their solute concentration. Water moves into the guard cells by osmosis, causing them to become turgid. The guard cells swell, causing the stoma to open. This allows CO₂ to enter while O₂ and water vapor leave.
A plant receives sufficient sunlight and CO₂ but still shows poor growth because it cannot obtain enough dissolved mineral nutrients from the soil. What concept explains why the plant's growth is reduced?
The mineral nutrients are acting as limiting factors. Even if other resources such as light and CO₂ are sufficient, inadequate availability of another required resource can limit plant growth.
Trace the sequence from a functional megaspore to formation of the embryo sac, including the number of mitotic divisions, nuclei, cells, and major cell types present.
The 1N functional megaspore undergoes three mitotic/cytokinesis divisions, producing 8 haploid nuclei but only 7 cells. The resulting embryo sac contains 3 antipodal cells, 2 synergids, 1 egg cell, and 1 central cell containing 2 polar nuclei. The embryo sac is the female gametophyte.