PCA WEEDS COMPREHENSIVE EXAM 2026 QUESTIONS
AND SOLUTIONS SCORED A+
✔✔List resources to assist in weed identification - ✔✔UC IPM, Weed Pest Identification
Monitoring Cards, CAC
✔✔Function of the xylem (apoplast) - ✔✔Nonliving tissue in plants that functions
primarily to conducct water and mineral nutrients from roots to the shoot
✔✔Function of the phloem (symplast) - ✔✔Living tissue in plants that functions primarily
to transport metabolic compounds such as sugars from the site of synthesis or storage
to the site of utilization
✔✔Function of chloroplast - ✔✔Contains chlorophyll which absorbs light energy for
photosyntheis
✔✔Function of membranes - ✔✔Provide a semi-permeable barrier & control the
movement of substances
✔✔Function of endodermis - ✔✔Ring of cells surrounds vascular cylinder
Cell walls are waterproof
Water can only enter vascular cylinder by moving through endodermal cells
Allows plant to control inward flow
✔✔Function of epidermis - ✔✔Outermost layer of cells covering all parts of the primary
plant body above and below ground
✔✔Function of cuticle - ✔✔prevents water loss
✔✔Function of apical meristem - ✔✔Meristem at the tip of the root or shoot in a
vascular plant, capable of cell division and plant growth
✔✔Function of root hairs - ✔✔these structures increase the surface area of the roots so
that they can absorb water efficiently
✔✔Function of root tip (meristem) - ✔✔Point of active cell division within roots
✔✔Function of stomata - ✔✔controls the entering and exiting of gases
✔✔Describe the conditions necessary for weed seeds to germinate - ✔✔Adequate
water, light, temperature
✔✔Compare how differing weed germination requirements affect management
decisions. - ✔✔Seedlings are most vulnerable, so different germination requirements
,will influence the management decision as to which method of germination will be used
pre- or post-plant
✔✔Define seed dormancy - ✔✔State in which viable seeds do not germinate. Seeds
have to break dormancy before germination.
✔✔Describe some factors that regulate or break seed dormancy -
✔✔Scarification/penetration of hard seed coat, chemical inhibition, temperature
✔✔Describe the effect of seed size on dormancy and the depth from which a weed
seed can successfully germinate. - ✔✔Larger seed can germinate from deeper depths.
Smaller seed can germinate from shallow depths.
Smaller seed is more persistent than larger seed and can remain dormant for longer
periods of time.
✔✔Annual Weed - ✔✔Weed plant that completes its life cycle in 1 year
✔✔Perennial Weed - ✔✔Weed that persists in the community by continuing to grow
year after year
✔✔Biennial Weed - ✔✔Weed that completes its life cycle in 2 years
✔✔Summer Annual Weed - ✔✔Weeds that germinate in the spring or early summer,
grow through summer, flower and set seed by autumn.
✔✔Winter Annual Weed - ✔✔Weeds that germinate in fall or early winter, grow during
the winter or spring, and flower and usually set seed by early to mid-summer
✔✔Dicot - ✔✔Plants with two cotyledons. Generally have net venation and flower parts
are usually found in multiples of four or five.
✔✔Monocot - ✔✔Plants with a single seed leaf. Most have leaves with parallel venation
and flower parts occurring in multiples of three
✔✔Describe the influence of seasonal changes on the weed spectrum - ✔✔Different
seasons will see different groups of weeds present in fields (winter vs summer annuals)
✔✔Describe the influence of weed growth on water and nutrient availability to the crop.
- ✔✔Weeds will out-compete crops for water and nutrient availability, hence why it is
important to manage weeds before they become out of control.
, ✔✔Describe the influence of temperature on plant growth. - ✔✔Warmer temperatures
will lead to increased plant growth but too hot of temperatures can damage plants and
retard their growth
✔✔Recognize the importance of light and space in plant growth and development -
✔✔Plants need space from other plants as well as adequate light to grow and develop
✔✔Reproductive capability of weeds - ✔✔Weeds can produce seed which can be
dispersed across space, or they can produce propagules which make them very
persistent and difficult to manage
Seeds are only way for annuals and biennials to reproduce.
Propagules are how perennials reproduce and allow for recovery from mechanical
damage.
✔✔Describe the mechanisms by which weed seeds are disseminated. - ✔✔Weed
seeds can be dispersed naturally by wind, water, and animals. They can also be
dispersed via tumbling weeds. They can also be dispersed by humans such as on
equipment, in soil on equipment, or seeds that puncture tires.
✔✔Describe how biotic factors of the environment contribute to regulating the seed
bank and seed longevity. - ✔✔Natural decay can break seed dormancy which if left
unmanaged can replenish the seed bank. Biotic factors can replenish the weed seed
bank.
✔✔Describe how loss of seed viability contributes to regulating the seed bank and seed
longevity. - ✔✔Loss of seed viability reduces the amount of weeds that are able to
germinate and reproduce more seed. If a seed bank were to theoretically become
unviable, there would be no weed problems.
✔✔Describe how production practices, such as applications of preemergence
herbicides, contribute to regulating the seed bank and seed longevity. -
✔✔Preemergence herbicides can reduce the amount of weeds that emerge and have
the potential to set seed, thus reducing the seed bank as well as seed longevity.
✔✔Describe how cultural practices contribute to regulating the seed bank and seed
longevity. - ✔✔Cultural practices, such as preirrigation or crop rotation, can reduce the
seed bank and longevity by germinating weed seeds to be cultivated, or rotating to a
crop that outcompetes the current weed seeds.
✔✔Describe how different types of vegetative propagules spread. - ✔✔When weeds
with vegetative propagules are fragmented, they can be spread to different fields or
parts of the field.
AND SOLUTIONS SCORED A+
✔✔List resources to assist in weed identification - ✔✔UC IPM, Weed Pest Identification
Monitoring Cards, CAC
✔✔Function of the xylem (apoplast) - ✔✔Nonliving tissue in plants that functions
primarily to conducct water and mineral nutrients from roots to the shoot
✔✔Function of the phloem (symplast) - ✔✔Living tissue in plants that functions primarily
to transport metabolic compounds such as sugars from the site of synthesis or storage
to the site of utilization
✔✔Function of chloroplast - ✔✔Contains chlorophyll which absorbs light energy for
photosyntheis
✔✔Function of membranes - ✔✔Provide a semi-permeable barrier & control the
movement of substances
✔✔Function of endodermis - ✔✔Ring of cells surrounds vascular cylinder
Cell walls are waterproof
Water can only enter vascular cylinder by moving through endodermal cells
Allows plant to control inward flow
✔✔Function of epidermis - ✔✔Outermost layer of cells covering all parts of the primary
plant body above and below ground
✔✔Function of cuticle - ✔✔prevents water loss
✔✔Function of apical meristem - ✔✔Meristem at the tip of the root or shoot in a
vascular plant, capable of cell division and plant growth
✔✔Function of root hairs - ✔✔these structures increase the surface area of the roots so
that they can absorb water efficiently
✔✔Function of root tip (meristem) - ✔✔Point of active cell division within roots
✔✔Function of stomata - ✔✔controls the entering and exiting of gases
✔✔Describe the conditions necessary for weed seeds to germinate - ✔✔Adequate
water, light, temperature
✔✔Compare how differing weed germination requirements affect management
decisions. - ✔✔Seedlings are most vulnerable, so different germination requirements
,will influence the management decision as to which method of germination will be used
pre- or post-plant
✔✔Define seed dormancy - ✔✔State in which viable seeds do not germinate. Seeds
have to break dormancy before germination.
✔✔Describe some factors that regulate or break seed dormancy -
✔✔Scarification/penetration of hard seed coat, chemical inhibition, temperature
✔✔Describe the effect of seed size on dormancy and the depth from which a weed
seed can successfully germinate. - ✔✔Larger seed can germinate from deeper depths.
Smaller seed can germinate from shallow depths.
Smaller seed is more persistent than larger seed and can remain dormant for longer
periods of time.
✔✔Annual Weed - ✔✔Weed plant that completes its life cycle in 1 year
✔✔Perennial Weed - ✔✔Weed that persists in the community by continuing to grow
year after year
✔✔Biennial Weed - ✔✔Weed that completes its life cycle in 2 years
✔✔Summer Annual Weed - ✔✔Weeds that germinate in the spring or early summer,
grow through summer, flower and set seed by autumn.
✔✔Winter Annual Weed - ✔✔Weeds that germinate in fall or early winter, grow during
the winter or spring, and flower and usually set seed by early to mid-summer
✔✔Dicot - ✔✔Plants with two cotyledons. Generally have net venation and flower parts
are usually found in multiples of four or five.
✔✔Monocot - ✔✔Plants with a single seed leaf. Most have leaves with parallel venation
and flower parts occurring in multiples of three
✔✔Describe the influence of seasonal changes on the weed spectrum - ✔✔Different
seasons will see different groups of weeds present in fields (winter vs summer annuals)
✔✔Describe the influence of weed growth on water and nutrient availability to the crop.
- ✔✔Weeds will out-compete crops for water and nutrient availability, hence why it is
important to manage weeds before they become out of control.
, ✔✔Describe the influence of temperature on plant growth. - ✔✔Warmer temperatures
will lead to increased plant growth but too hot of temperatures can damage plants and
retard their growth
✔✔Recognize the importance of light and space in plant growth and development -
✔✔Plants need space from other plants as well as adequate light to grow and develop
✔✔Reproductive capability of weeds - ✔✔Weeds can produce seed which can be
dispersed across space, or they can produce propagules which make them very
persistent and difficult to manage
Seeds are only way for annuals and biennials to reproduce.
Propagules are how perennials reproduce and allow for recovery from mechanical
damage.
✔✔Describe the mechanisms by which weed seeds are disseminated. - ✔✔Weed
seeds can be dispersed naturally by wind, water, and animals. They can also be
dispersed via tumbling weeds. They can also be dispersed by humans such as on
equipment, in soil on equipment, or seeds that puncture tires.
✔✔Describe how biotic factors of the environment contribute to regulating the seed
bank and seed longevity. - ✔✔Natural decay can break seed dormancy which if left
unmanaged can replenish the seed bank. Biotic factors can replenish the weed seed
bank.
✔✔Describe how loss of seed viability contributes to regulating the seed bank and seed
longevity. - ✔✔Loss of seed viability reduces the amount of weeds that are able to
germinate and reproduce more seed. If a seed bank were to theoretically become
unviable, there would be no weed problems.
✔✔Describe how production practices, such as applications of preemergence
herbicides, contribute to regulating the seed bank and seed longevity. -
✔✔Preemergence herbicides can reduce the amount of weeds that emerge and have
the potential to set seed, thus reducing the seed bank as well as seed longevity.
✔✔Describe how cultural practices contribute to regulating the seed bank and seed
longevity. - ✔✔Cultural practices, such as preirrigation or crop rotation, can reduce the
seed bank and longevity by germinating weed seeds to be cultivated, or rotating to a
crop that outcompetes the current weed seeds.
✔✔Describe how different types of vegetative propagules spread. - ✔✔When weeds
with vegetative propagules are fragmented, they can be spread to different fields or
parts of the field.
