LAB MANUAL CHAPTER 2: PHENOTYPIC PLASTICITY

Question 1

Phenotypic Plasticity

Answer 1

• the observable manifestation of a genotype
• includes the morphology, physiology, and behaviors of an organism
• if there is variation in the phenotype of individuals in a population, then there might be variation in the genotype or even in the phenotype
• can be encoded for by one or more alleles

Question 2

Evolution - Phenotype and Genotype

Answer 2

• it may appear that a phenotype is passed down from one generation to the next but rather it is the genetic alleles that are being passed down - the genotype

Question 3

Genotype

Answer 3

The genetic constitution of an organism

Question 4

Acclimation

Answer 4

The ability of an individual to adjust their phenotype in response to variation in the environment in order to increase their fitness

Question 5

Phenotypic Plasticity

Answer 5

The ability of an individual to adjust a specific trait in response to their environment in order to increase their fitness implies that the trait is phenotypically plasticity (or there is phenotypic plasticity of the trait)

Question 6

How Phenotypic Plasticity can be Expressed

Answer 6

• Can be expressed in discrete traits or in a continuum
  Take a desert plant for example
• If there seeds are yellow or green with no in-between, then the trait is discrete
• If we are looking at how the number of nodules on its legumes changes, then we are looking at a continuous trait

Question 7

Reaction Norm

Answer 7

If there is phenotypic plasticity of a continuous trait, then the relationship between the environment and the given trait is known as REACTION NORM

Question 8

Why Aren’t All Traits Phenotypically Plastic?

Answer 8

• There is insufficient genetic variation for all traits to be phenotypically plastic
• If there is an abundance of phenotypic plasticity, this could impose selection against phenotypically plastic traits
• if many genes are phenotypically plastic, this could essentially imply that the genes have the potential to be good for one thing and very bad for another and reduce the fitness of another trait

Question 9

How Could Selection Lead for Plasticity of a Trait

Answer 9

Phenotypic plasticity would be extremely beneficial in heterogeneous environments as the organisms would have to acclimate to a variety of conditions and climates

Question 10

History of Jagged Ambush Bugs

Answer 10

• Peak Activity in the Summer Seasons
• Males seek out females while females wait until males look for them
• males stridulate the females and if the females accept, the males attach laterally to the females and that is how copulation occurs
• STRIDULATION: the rubbing together of two body parts
• jagged ambush bugs are also able to catch their prey and pierces them with the ROSTRUMS (a beak-like mouthpiece) and inject their prey with enzymes
• jagged ambush bugs have two light-sensitive organs: compound eyes and simple eyes

Question 11

Calculating the Width of Ocular Width

Answer 11

1. Set up the width of the ocular micrometer
2. Align the lines of the ruler with the ocular micrometer and divide how much a certain amount of ocular lines expands over the number of lines.
   for example, if ten lines expand a range of 1 mm, the ocular width of each space would be 1mm/10 units

Question 12

Phenotypic Response in Plants

Answer 12

With variation in the amount of sunlight a plant is exposed to, the thickness of its leaves will thus be affected

Question 13

Our Lab

Answer 13

Independent variable: the amount of sunlight
Dependent variable: the thickness of the leaves
Hypothesis: The amount of sunlight a plant is exposed to effects the thickness of the leaves
Null hypothesis: the amount of sunlight a plant is exposed to does not affect the thickness of the leaves
Predictions: There is a positive correlation between the amount of sunlight a plant is exposed to and the thickness of the leaves

Question 14

Lab discussion

Answer 14

There was a positive correlation between the two variables thus imply that while the genotypes of the plant remain the same, we are able to variation and thus phenotypic plasticity in the trait given variation in the environment. This is adaptive due to the fact that the mesophyll of a leaf expands to prevent the overheating of the chloroplasts.

Question 15

Cuticle

Answer 15

the waxy layer at the top of a leaf that prevents water loss

Question 16

Upper Epidermis

Answer 16

the layer of the plant that is used to absorb sunlight

Question 17

Mesophyll - Palisade and Spongy

Answer 17

contains many membrane-bound organelles including chloroplasts. expands in order to prevent the overheating of the chloroplasts

Question 18

Stomata and Guard Cells

Answer 18

Stomata are air openings for gas exchange in the guard cells which are found at the bottom of the plant