Plant Growth and Development Exam 1

When a shoot reaches a predetermined size the plant ceases to get larger.

Determinate growth

There is no set endpoint for plant size.

Indeterminate growth

The cycle of growth and flowering is repeated year after year with the plant surviving the winter by storage organs or with perenating buds.

Perennial growth

The plant grows vegetatively the first year, initiates flowering the second year before flowering, setting seed, and dying the second year.

Biennial growth

The plant grows and reaches maturity producing flowers and seeds in one growing season.

Annual growth

In the vegetative state, the levels of RNA are lower in the center zone cells then surrounding cells. Synthesis of RNA in this region is reported to be less active than in the peripheral zone because _____.

these cells are relatively inactive and divide infrequently in the vegetative state.

Cells in he tunica layers primarily divide at right angles to the surface or _____.

anticlinally

The cells in the two to five outermost layers of the apical meristem are referred to as the _____.

tunica (or tunica layers)

The corpus of the apical meristem is divided into three zones.

Central zone, Peripheral zone, and Rib meristem

Procambial cells normally give rise to vascular tissues, pericycle, and vascular cambium and would be found in which part of the apical meristem?

Peripheral zone

The average size of vegetative apical meristem is _____.

100-250

True/False: The time interval between the initiation of two successive leaves is called a plastochron.

True

True/False: Differentiation is the process whereby cells from a common origin become different.

True

When the center of the apical meristem is isolated by making 3-4 deep vertical incisions leaving it attached to the rib meristem but served from the peripheral zone and leaf primordia, it continues growing and in time will develop new leaf primordia, give rise to the normal tissues of the shoot. This is evidence that the meristem is _____.

autonomous

True/False: In embryo dormancy, the removal of seed coat (testa) will result in germination.

False

Seeds that have a specific requirement for light for germination are referred to as photoblastic seeds. These seeds require a brief exposure to red light while imbibed. What is the photoreceptor involved in this response?

Phytochrome

Breaking dormancy by exposing imbibed seeds to cold (2 -5C) temperatures is a process called cold stratification. Cold stratification varies by species and ecotype and works by _____________.

-Leaching ABA and other germination inhibitors

-Giving rise to gibberellin-like substances

-Decreasing the embryo's sensitivity to ABA and other inhibitors

Weakening the physical barrier (i.e. seed coat) to radicle protrusion by enzymes synthesized or activated by low temperatures

Select all of the following phytochrome combinations which stimulated germination in the chart discussed in lecture.

-Gibberellins + Cytokinins + Abscisic Acid

-Gibberellins + Cytokinins

-Gibberellins

True/False: Gibberellins in the seed alurone layer stimulates the release of the starch during seed germination.

False

Freshly harvested seeds of many plants will not germinate or germinate poorly. They require a period of warm, dry storage for a few weeks to a few months depending on species. This process is known as __________.

Afterripening

Seeds can be viable for _____.

a few weeks to hundreds of years.

Phase I

Activation and hydration of mitochondrial enzymes

Phase II

Respiration plateau due to low oxygen

Phase III

Increase in oxygen from new mitochondrial enzymes causing aerobic respiration of carbohydrates

Phase IV

Respiration decreases as seedling emerges and starts photosynthesis

What are environmental factors that affect germination?

-Water

-Temperature

-Aeration

-Light

Which of the plant hormones is most thought to play a important role in the degradation of the suspensor by causing senescence of these cells?

Absisic acid

True/False: Somatic embryogenesis is the production of embryos and eventually whole plants, from single vegetative cells. This confirms the theory that plant cells can set up their own polarity.

True

Monocot embryogenesis differs from Dicot embryogenesis in that _____.

there is no heart stage in monocots because they have only one cotyledon

The concept exists that nearly all plant cells totipotent. What does this mean?

All plant cells with a functional nucleus are capable of giving rise to a whole plant.

Much the same effect of leaving the suspensor intact can also be accomplished with the addition of which plant hormone to the culture medium?

Gibberellic acid

Which of the following is not a valuable function of somatic embryogenesis?

Seed production in plants

The progressive pattern of development from a fertilized zygote to a mature seed is suggestive of the progressive and sequential activation of _____.

genes

As the embryo develops, cellular organs become more active and more organized around the nucleus. However, as the cell number increases what happens to the cells?

The cells decrease in size by half with each successive division.

As the embryo matures and seed start to ripen, the maturing seed's dry weight stays constant but the fresh weight declines. This is due to _____.

the maturing seed loosing water and desiccating to 10-15% moisture content.