Bio Test 4 (Ch.14)

A mouse would be expected to have the shortest gestation period compared to the other mammals listed. This is because mice are small mammals and generally have shorter gestation periods compared to larger mammals like elephants, giraffes, chimpanzees, and humans. The gestation period of a mouse is typically around 19-21 days, whereas larger mammals have longer gestation periods ranging from several months to over a year.

Life histories are based on various factors such as the age at death, the age of reproduction and number of reproductive events, litter size, and the rate of growth and development. These factors collectively contribute to understanding the life history of an organism. The age at death provides information about the lifespan, while the age of reproduction and number of reproductive events indicate the reproductive strategy. Litter size is a crucial aspect of reproductive success, and the rate of growth and development reflects the overall life cycle of the organism. Therefore, all of the mentioned factors are considered while studying life histories.

The age-structure diagram of a human population in a developing country has the shape of a pyramid. This indicates that the population has a high proportion of young individuals and a decreasing proportion of older individuals. This is typically seen in countries with high birth rates and limited access to healthcare and education. As the population progresses and development occurs, the pyramid shape may shift towards a more rectangular shape, indicating a more balanced age distribution.

When a population exceeds its carrying capacity, two possible outcomes are likely to occur. Firstly, the population may slowly decline until it reaches its carrying capacity. This decline is due to limited resources and increased competition for those resources. Secondly, the population may shoot past its carrying capacity too quickly, leading to a sudden crash. This rapid increase in population can deplete resources rapidly, causing a sharp decline in population numbers. Both scenarios, a gradual decline and a sudden crash, are possible when a population exceeds its carrying capacity.

The annual birth rate can be calculated by dividing the number of offspring produced during the year (125) by the initial population (500). This calculation gives us a birth rate of 0.25, which means that on average, each individual in the population produces 0.25 offspring per year.

A population with an S-shaped growth curve is said to exhibit logistic growth. This type of growth occurs when a population initially grows rapidly, but eventually levels off and stabilizes at the carrying capacity of its environment. This is in contrast to exponential growth, which is characterized by continuous and unrestricted growth. Logistic growth is influenced by factors such as limited resources and competition, making it a density-dependent process.

As of 2008, the approximate number of humans living on Earth was 6 billion.

Disease being spread more quickly between individuals who live in close proximity suggests that it is influenced by the density of the population. This is because the closer individuals are to each other, the easier it is for the disease to spread from one individual to another. Therefore, disease can be considered a density-dependent factor, as its impact is dependent on the density or closeness of the population.

Exponential growth occurs when a population grows at an accelerating rate, proportional to its current size. This means that as the population gets larger, it grows even faster. In this scenario, the population is not limited by any factors such as available resources or competition, so it can continue to grow without any constraints. Therefore, the correct answer is exponential growth.

The term "carrying capacity" refers to the maximum number of individuals that a habitat can sustain indefinitely. It represents the balance between available resources and the population's needs. When a population exceeds its carrying capacity, it can lead to resource depletion and negative impacts on the environment. Therefore, the correct answer is carrying capacity.

The correct answer is "none of the above; all are part of an organism's life history." This means that all the options listed (death, birth, growth to maturity, and size) are included in an organism's life history. The life history of an organism encompasses its entire life cycle, including its birth, growth, reproduction, and death. Additionally, factors such as size can also be important in understanding an organism's life history, as it can influence its behavior, survival, and reproductive strategies. Therefore, all of these elements are considered part of an organism's life history.

The per capita birth rate of 0.8 means that on average, each individual beetle gives birth to 0.8 offspring in a year. The per capita death rate of 0.5 means that on average, each individual beetle dies at a rate of 0.5 per year. To estimate the number of individuals added or lost from the population, we subtract the death rate from the birth rate and multiply it by the initial population size. In this case, (0.8 - 0.5) * 1000 = 0.3 * 1000 = 300 individuals added.

When the hare population size grows, more food is provided for the lynx. This increase in available food allows the lynx to have better access to resources, leading to improved reproductive success. As a result, the lynx population will reproduce at a higher rate in order to take advantage of the abundant food supply. This increase in lynx reproduction is the immediate next step in the cycle of population growth between lynx and snowshoe hare.

Humans have avoided growth beyond their carrying capacity through various mechanisms. They have been able to live in higher densities than before, which allows for more efficient use of resources. Additionally, humans have expanded into new habitats, which has provided them with access to additional resources. Furthermore, the ability to cure previously fatal diseases has increased human survival rates, preventing population growth from exceeding carrying capacity. Lastly, advancements in agricultural practices have enabled humans to produce more food than previously possible, supporting larger populations. Therefore, all of the given options are mechanisms by which humans have avoided reaching their carrying capacity.

Natural selection can only act on traits that affect an individual's reproductive success. If an allele increases an individual's risk of dying but does not impact their ability to reproduce, natural selection cannot eliminate it from the population. This is because the allele does not directly affect an individual's relative reproductive success. Therefore, even if the allele increases the risk of dying, it will not be weeded out by natural selection.

The population size at time t+2 will be larger than the initial population size at time t because the growth rate (r) is greater than 1. The growth rate of 1.05 indicates that the population is increasing by 5% per generation. Therefore, the population size at time t+2 will be 105 multiplied by 1.05, resulting in a population size of 110.

The statement "it will exceed 7 billion if the current rate of increases continues" best describes expectations for world human population by the year 2010. This suggests that based on the current rate of population growth, the world population is projected to surpass 7 billion.

Life-history patterns are subject to the pressures of natural selection because they are traits that affect an organism's survival and reproductive success. These patterns, such as the timing of reproduction, number of offspring produced, and lifespan, are influenced by environmental factors and the availability of resources. Organisms with life-history patterns that are better adapted to their environment are more likely to survive and pass on their genes to the next generation, leading to the evolution of these traits over time.

In the age-pyramids of industrialized countries, the proportion of the population in the youngest age group is smaller compared to third-world countries. This means that third-world countries have a higher percentage of young individuals in their population. This could be due to factors such as higher birth rates, limited access to healthcare and family planning, and lower life expectancy.

The correct answer is "is a group of coexisting organisms capable of interbreeding." This definition accurately describes a population as a group of organisms of the same species that live in the same area and are capable of reproducing with one another. This definition emphasizes the importance of interbreeding as a defining characteristic of a population. It distinguishes a population from a community, which consists of interactions between different species, and from a habitat, which refers to a specific environment where organisms live.

In a population exhibiting logistic growth, the rate of population growth is greatest when the population size (N) is at half of the carrying capacity (0.5 K). This is because at this point, the population is growing at its maximum potential rate due to the optimal balance between available resources and population size. As the population size increases beyond half of the carrying capacity, the rate of growth starts to slow down due to limited resources and increased competition. Similarly, when the population size is below half of the carrying capacity or at 0, the rate of growth is also lower as there are still ample resources available for the population to grow.

The statement that the maximum sustainable yield for a population is a useful management guideline for harvesting plant products such as timber, but it is not helpful for managing animal populations is incorrect. The concept of maximum sustainable yield is applicable to both plant and animal populations and can be used as a management tool for sustainable harvesting and conservation of natural resources.

The given statement is not true because individuals within a population do not undergo genetic change. Genetic changes occur through the process of evolution, which happens over multiple generations and affects the population as a whole. While individuals may have genetic variations, it is the population as a whole that undergoes genetic change through mechanisms such as natural selection, genetic drift, and gene flow.

As the population size approaches the carrying capacity of the environment, the resources available for the population become limited. This leads to increased competition for resources and a decrease in the rate of population increase. Eventually, the rate of population increase approaches zero as the population reaches its maximum sustainable size.

A survivorship curve that had low survivorship in the beginning and stabilized after high initial mortality would be characteristic for cod. Cod are a type of fish that typically experience high mortality rates during their early life stages, with many individuals dying shortly after hatching. However, those that do survive this initial period have a higher chance of reaching adulthood and have a relatively stable survivorship rate thereafter. This pattern is commonly observed in species with high reproductive output but high juvenile mortality rates, such as fish species like cod.

A population model is a tool used to predict or explain changes in the abundance of organisms from one generation to the next. It helps in understanding how factors such as birth rates, death rates, immigration, and emigration affect the population size. By using mathematical equations and statistical methods, population models can estimate future population trends and provide insights into the dynamics and behavior of populations. These models are crucial in ecological research, conservation planning, and management of endangered species.

When N equals K, population growth is zero. This is because N represents the population size, and K represents the carrying capacity of the environment, which is the maximum number of individuals that the environment can support sustainably. When the population size (N) equals the carrying capacity (K), it means that the population has reached its maximum sustainable size, and there is no more room for growth. At this point, the birthrate equals the death rate, resulting in zero population growth.

The fact that lynx pelts are better for keeping trappers warm in the winter and that trappers kept more of the lynx pelts for themselves suggests that the population of lynx and snowshoe hare actually exhibited the oscillating pattern shown. This is because if the populations were not actually oscillating, there would be no reason for trappers to selectively keep more lynx pelts. The preference for lynx pelts indicates that there were periods when the lynx population was larger and the hare population was smaller, leading to an increase in lynx pelts available for trapping.

Exponential growth cannot continue indefinitely because it is limited by the carrying capacity of the habitat. The carrying capacity is the maximum population size that can be sustained by the available resources in the habitat. As the population size approaches the carrying capacity, resources become limited and growth slows down until it eventually levels off. Therefore, none of the given options are correct as they do not account for the limitation imposed by the carrying capacity.

Larger animals generally have a longer generation time because they take longer to reach sexual maturity and reproduce. This is due to their slower growth rate and longer lifespan compared to smaller animals. As body size increases, the time required for development and reaching sexual maturity also increases, resulting in a positive correlation between body size and generation time. However, it is important to note that this correlation levels off after reaching a certain body size, indicating that there is a limit to how much body size affects generation time.

not-available-via-ai

In 1900, the world had a human population of approximately 1.6 billion. This means that there were around 1.6 billion people living on Earth during that time. In 2000, the world had a human population of approximately 6.1 billion. This means that there were around 6.1 billion people living on Earth during that time.

A population model is a tool used to predict or explain changes in the abundance of organisms from one generation to the next. It helps scientists understand how factors such as birth rate, death rate, migration, and environmental changes can affect the size and dynamics of a population over time. By using population models, researchers can make predictions about the future of a population and develop strategies for conservation and management.

In the year 1950, the human population of the world was approximately 2.5 billion.

The correct answer is "lower after the organisms survive to the critical age of establishment." In a type 3 survivorship curve, the death rate is high for young organisms but decreases significantly once they reach a certain age. This critical age of establishment is when the organisms have overcome the initial challenges and have a higher chance of survival. After this age, the death rate tends to be lower, indicating that the organisms have a higher likelihood of surviving and reaching reproductive age.

The most likely factor that contributed to the dramatic increase in growth rate from 10,000 to 5,000 years ago is the change from a nomadic to a more settled lifestyle, making larger families more manageable. This change would have allowed people to have a more stable and secure environment, which would have made it easier to raise larger families. In a nomadic lifestyle, it would have been more difficult to provide for and care for larger families, which could have limited population growth. By transitioning to a settled lifestyle, people would have had access to more resources and support systems, allowing them to have more children and ultimately leading to a higher population growth rate.

The correct answer is that if both populations are stable, then the pair of elephants and the pair of rabbits will leave the same number of offspring that survive to become adults and reproduce. This is because the question states that the average number of offspring that survive to become adults and reproduce is being compared, and if both populations are stable, it means that the survival and reproduction rates are similar for both elephants and rabbits. Therefore, the number of offspring that survive to become adults and reproduce will be the same for both species.

The demographic transition refers to the shift in population from high birth and death rates to low birth and death rates. This transition occurs as a result of various factors such as improved healthcare, education, and economic development. As societies progress, they tend to experience a decrease in both birth and death rates, leading to a more stable population growth. Therefore, the correct answer is "low birth rates and low death rates."

The demographic transition refers to the changes in birth and death rates that occur as a population becomes industrialized. Initially, the death rate decreases due to improvements in healthcare and living conditions. This is followed by a decrease in the birth rate as people have access to contraception, education, and better economic opportunities. This transition is a common pattern observed in many countries as they develop economically and socially.

Some countries have more resources than their populations can currently use. This means that these countries have a surplus of resources, which indicates that their carrying capacity is not being fully utilized.

The hazard factor of a population is not higher for a population of porcupines than for a population of guinea pigs. The hazard factor is a measure of organisms' risk of death from external sources, not a measure of how quickly the individuals in a population age. It is responsible for the rate of aging among the individuals in a population. Additionally, it is relatively low when populations have few predators. Therefore, the correct statement is that the hazard factor is higher for a population of porcupines than for a population of guinea pigs.

The logistic model of growth incorporates environmental limitations on population size. This means that as the population approaches its carrying capacity, the growth rate slows down and eventually stabilizes. On the other hand, exponential growth models do not take into account any limitations on population size and assume unlimited resources. Therefore, exponential growth can continue indefinitely without any constraints. In nature, long-term exponential growth is less commonly observed compared to long-term logistic growth, as most populations eventually reach their carrying capacity and stabilize.

Cold exposure due to suitable nesting sites being occupied is not a density-independent population regulating factor because it is dependent on the availability of nesting sites. Density-independent factors are those that affect population size regardless of the population's density, such as variable winter weather, fire, flooding, and reduced food availability due to drought. These factors can impact population size regardless of how many individuals are present in the population.

In high-predation sites, guppies face a higher risk of being eaten by predators. In order to increase their chances of survival and reproduce successfully, guppies living in high-predation sites are likely to evolve larger egg sizes. Larger eggs have a higher chance of survival and can provide more nutrients and energy to the developing offspring, increasing their chances of survival in a risky environment. This adaptation allows guppies to allocate more resources towards producing fewer, but larger, offspring that have a higher chance of survival.

During logistic growth, the per capita rate of increase approaches zero after the population reaches one-half the carrying capacity. This is because as the population size approaches the carrying capacity, resources become limited and competition for those resources increases. As a result, the rate of population growth slows down and eventually reaches zero when the population size reaches half of the carrying capacity. This is known as the inflection point, after which the population growth starts to decline and eventually stabilizes at the carrying capacity.

not-available-via-ai

This statement is correct because there is indeed a tradeoff between the number of offspring an organism can produce and the amount of care it can provide for its offspring. This tradeoff is known as the "cost of reproduction" and is one of the inherent tradeoffs in life history strategies. Organisms that produce a large number of offspring may not be able to provide as much care for each individual offspring, while organisms that provide a lot of care for their offspring may have fewer offspring. This tradeoff is a result of limited resources and energy available to the organism.