Tutor profile: Caitlin S.
What is the pH of a buffer consisting of 0.50M CH3COOH and 0.50M CH3COONa? (Ka of CH3COOH = 1.8 x 10 ^-5)
To answer this question of a weak acid buffer solution, we will use the Henderson-Hasselbach Equation. pH = pKa + log [base]/[acid]. When a solution is in the buffer range (as the question states) the concentration of the acid and conjugate base is equal. This gives [base]/[acid] value of 1. Therefore the pH = pKa and to find the pKa we need to use the formula pKa= -log(Ka). the Ka of this weak acid was given, therefore to solve this question, we take the -log(1.8 x 10 ^ -5) = pKa. pKa= 4.74 pH= 4.74
Describe the structure and composition of terrestrial communities and the ecological processes that affect their dynamics. Include examples.
Terrestrial communities include all populations of species within a certain area, these can vary in size and boundaries. The structural components of terrestrial communities are mainly composed of plants, animals and micorbes, typical distinguished by their trophic levels. Their are often two important patterns in community structure, open and closed communities. Open communities are often populations that can exist in a wide range of environment conditions and do not show higher distributions in particular conditions. These populations are distributed more or less randomly, often immune to abrupt transitions in the physical environment. An example would be deciduous forests. These populations exist in an open community because they have no natural boundaries. In a closed community, it often has populations that occur only in a similar geographic range and present distinct density peaks. They form pretty clear sharp boundaries, and are called ecotones. For example, the ecotone that develops between alpine and sub-alpine elevations on a mountain range. Because photosynthesis is the most prevalent fundamental biological process that converts radiant energy to chemical energy thus making it available to all living things, primary production determines the distribution, abundance, and diversity of consumers that live reliant on the photosynthetic products of plants in the terrestrial ecosystem. The ecological processes that effect their dynamics include water and nutrient availability, climate, plant defenses, environmental heterogeneity, disturbance from natural disasters and herbivores, and predator-prey cycles. Terrestrial biotic communities dynamics are dependent on the productivity gradients of the habitats. For example, the primary productivity of a desert ecosystem where water is a limiting factor is less functionally diverse and complex than a tropical rain forest ecosystem where the soil is productive and water is available.
In regards to the study of primates, explain the relationship between locomotion, anatomy and environment?
Primate anatomical traits typically vary as a response to their environment, but a few general characteristics arise. Their limbs and locomotion have a tendency towards an erect posture, and they have versatile and generalized limb structure. This is to accommodate various locomotive behaviors, their environment and dietary preferences such as foraging in trees or on the ground. They also have the ability to grasp objects, such as tree branches, and manipulate objects. This prehensility is defined by primate retention of five digits on their hands and feet, opposable thumbs and big toes (non-human primates), the presence of nails rather than claws, tactile pads, and a powerful grip defined by its precision. Limb length is correlated with the locomotory patterns that are diverse among order primate. Vertical leaping and climbing are common in forested environments, primates will grasp trunks and branches using their forelimbs and spring off using their hindlimbs. This results in a general characteristic of longer hindlimbs compared to forelimbs. Another common locomotion pattern is brachiation, also known as arm swinging. The primate suspends themselves from branches. To aid in this form of movement they have long forelimbs and extended curved fingers, with short hindlimbs. The final locomotory pattern, quadrpedalism, can vary depending on the environment they inhabit. Primates that exhibit quadrapedalism use all four limbs to support their body during locomotion. They can occur in both terrestrial and arboreal environments. A common characteristic is knuckle walking for terrestrial inhabitants and in all environments, the limb lengths are roughly equal.
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