It is proposed that modern coal deposits mostly derive from the Carboniferous pe

Question

It is proposed that modern coal deposits mostly derive from the Carboniferous period because A) Algae in ocean surrounding the Pangea supercontinent settled to the oxygen-poor depths, where it 19) became petrified as coal B) Plant cell walls in the extensive forests became petrified because of sudden cooling and drying of the environment C) Plants evolved lignocellulosic cells walls -80 million before white rot fungus evolved the ability to efficiently degrade these structures D) The warm wet climate supported the most prolific forests the world has ever had E) Ca2+ was more prevalent because of extensive weathering of rock and volcano action, making plant cell walls stronger and more resistant to degradation. 20) In the context of plant cell walls, explain what is happening when making homemade jam (i.e., heating fruit in a jar to convert intact fruit to a gelled matrix) (1 pt). 21) Explain why adding calcium (Ca, from Tums, etc.) while making homemade jam would help make the jam thicker and stiffer (1 pts) In a signal transduction cascade, the receptor is usually located A) In the nucleus 22) B) on the plasma membrane C) Anywhere the signal can reach D) In the cytoplasmE) On the leaf surface Which statement is most FALSE regarding signal transduction cascades in plants A) Signal transduction cascades interact with each other B) Signal transduction cascades can work over very short or very long distances C) Plant cascades are usually a series of positive activation steps D) Plant cascades usually involve the inactivation of a repressor E) The receptor for a hormone may be part of the ubiquitination process targeting a repressor for 23) degradation 24) The expression "one bad apple ruins the bunch" can be applied figuratively to a disruptive student in a lecture hall, but in literal, botanical terms, this expression refers to the action of A) Ethylene B) Auxin C) Cytokinin D) Gibberellic acid E) Abscisic acid

Explanation / Answer

19) C) Plants evolved lignocellulosic cell walls 80 million before white rot fungus evolved the ability to efficiently degrade these structures.

It is proposed that large quantities of wood was buried during carboniferous period as organisms had not evolved the enzymes that could efficiently digest the resistant phenolic lignin and suberin polymers.

20) Pectin is a polysaccharide found in the plant cell walls and mostly in the skin of fruits. It is water soluble and binds with sugar and acids to form gel which shortens or eliminates the cooking time resulting in jam or jelly with fresher fruit flavour

21) Pectin needs calcium to activate it.

22) C) Anywhere the signal can reach.

Signal mediators often bind to membrane bound receptors outside the cell or diffuse inside the cell and bind to receptors in the cytoplasm or on the nuclear membrane.

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