ReproductionName
During double fertilization, one sperm forms the zygote. What does the second sperm nucleus fuse with?
The two polar nuclei in the central cell
What is the main force that pulls water upward in xylem?
Transpiration pull
Which hormone is primarily responsible for fruit ripening?
Ethylene
What factor limits exponential growth in natural populations?
Limited resources
What is interspecific competition?
Competition between different species
Why is double fertilization considered energy efficient for flowering plants?
Endosperm forms only if fertilization occurs
Why does water move from soil into root hairs?
Water potential gradient (osmosis)
What causes a plant stem to bend toward light?
Uneven auxin distribution causing differential growth
What does carrying capacity represent?
Maximum population size environment can support
What is the role of a decomposer in an ecosystem?
Breaks down dead organic matter
A flower with stamens but no carpels would be classified as what?
Incomplete flower
What is the function of aquaporins in plant cells?
Facilitate water movement across membranes
What type of tropism is root growth downward in response to gravity?
Gravitropism (positive)
What type of survivorship curve shows high early mortality
Type III
Why do invasive species often spread rapidly in new environments?
Lack of natural predators
What is the biological advantage of seed dormancy?
Allows germination only when conditions are favorable
Why does water flow more easily through xylem than phloem?
Xylem is dead and hollow, reducing resistance
Why do plants close stomata during drought conditions?
To reduce water loss
Why do populations often fluctuate around carrying capacity?
Resource availability and environmental resistance
What is mutualism?
Both species benefit from interaction
Why might passage through an animal digestive tract promote germination?
It scarifies the seed coat
How does stomatal opening affect transpiration rate?
Increases water loss through evaporation
What is the ecological advantage of seed dispersal mechanisms?
Reduces competition with parent plant
What is the difference between K-selected and r-selected species?
K-selected have fewer offspring with higher survival; r-selected produce many with low survival
How can disturbances affect ecological succession?
Reset community and allow new species establishment