High school biology questions about the rate of population growth

Why should you consider the two factors separately? = =!

During T1(T0) T2, food was relatively abundant and intraspecific struggles were not violent. With the increase of the population base, the growth rate of birth rate is greater than that of mortality rate, so the population growth rate increases.

During T2 T3 (T4), there is a shortage of food and intraspecific struggles intensify. With the further increase of the population base, the food pressure is greater, and the growth rate of mortality is greater than that of the birth rate, so the growth rate of the population gradually decreases.

Both the J-shaped curve and the S-shaped curve refer to the change in the number of biological populations, as shown in the figure: Growth rate: The growth rate refers to the rate of change in the population per unit time, that is, the ratio of the number of individuals in the population that has increased net in a unit time to the total number of individuals.

Growth rate (number of existing individuals, number of existing individuals) number of original individuals, birth rate-death rate (number of births, number of deaths) (number of units per unit of time). In populations with a "J" curve growth, the growth rate remains constant; In the "S" shaped growth curve, the growth is getting bigger and bigger, and then getting smaller and smaller.

Growth rate: Growth rate refers to the number of population growth per unit time.

Growth rate (number of existing individuals Number of original individuals) Growth time = (number of births and deaths) unit time]. The rate of population growth is the tangent slope of each point on the curve, and the slope on both the "J" and "S" curves is always changing. In the population with a "J" curve growth, the growth rate is gradually increasing.

In populations with an "S" curve growing, the "growth rate" is the slope of the tangent of "a point" on the curve, the greater the slope, the greater the growth rate, and the slope is at the maximum at "1 2k". After that, the growth slows down, and the rate of growth gradually decreases. When the "s" curve reaches the k value, the growth rate is 0

, the growth rate of the "J" curve is constant, while the growth rate is increasing all the time. The growth rate of the "S" curve is gradually decreasing, and the growth rate is first rising and then decreasing. The rate of growth can be expressed by the slope of the point, such as.

The growth rate of the "S" curve reaches its maximum at k 2.

Growth rate (number of existing individuals, number of original individuals) Growth time.

Growth rate (number of existing individuals, number of original individuals) number of original individuals, birth rate, mortality rate.

Growth rate is like a velocity formula, it has to do with time.

Population growth rate and growth rate in the S" curve.

Still taking a certain animal as an example, in nature, because the environmental conditions are limited, the population cannot grow according to the "J" curve, but in a limited environment, with the increase of population density, the struggle for survival intensifies, the birth rate decreases, and the mortality rate increases, so that the growth rate of the population decreases, and when the population reaches the maximum value (k) allowed by the environment, the population stops growing, and sometimes it remains relatively stable around the k value, then the population growth curve of the population in the 0 t years shows an "S" shaped growth.

If the "S" shaped growth curve is converted into the corresponding population growth rate curve, that is, the ordinate is changed to the population growth rate, then according to the concept of population growth rate analysis, the growth rate (the end of the initial number) The initial number is 100, although the absolute number of population growth per unit time is not much, but because the initial number is small, the ratio of the two is still large, so the population growth rate is higher, and later, although the absolute number of population increase per unit time increases, because the base of the previous year, that is, the initial number, is also large. Therefore, the ratio of the two decreases compared with the previous year, and when the population is close to the environmental capacity, the population number basically does not increase, that is, the last number-initial number is close to 0, and the population growth rate is gradually close to 0, and when the environmental capacity is reached, it is 0

If the "S" shaped growth curve is converted into the corresponding population growth rate curve, that is, the ordinate is changed to the population growth rate, then according to the population growth rate = (end number and initial number) unit time analysis, the population growth rate is also small because the absolute number of population increase per unit time (i.e., the end number - the beginning number) is small at the beginning. According to the analysis of the logistic curve ("S" curve), when the population reaches k 2, the absolute number of population increases per unit time is the largest, so the population growth rate is the largest (equivalent to the slope of the curve). Subsequently, when the population number exceeds k 2, the population growth rate slows down, and the population growth rate decreases, and when the population number is k, the population no longer increases per unit time, so the population growth rate is 0

Features of the "S" type growth curve model:

Population growth rate: Since there is no fixed formula for the change law of the "S" shaped growth curve, it can only be analyzed theoretically. Since the rate of population growth is equivalent to the slope of the curve, it can be judged that it increases first and then decreases through observation.

Population growth rate:

Due to the influence of environmental conditions on population population, the population growth rate is gradually decreasing as the population density increases gradually and proportionally, and the difficulty of population increase increases.

Fishing conditions were at their best. Capture does not affect its racial continuity. Because the harvest is the fastest growing, it can return to its original quantity in the shortest possible time after harvesting.

You confuse the growth rate with the growth rate, the growth rate = birth rate - death rate, and the growth rate of the S-shaped curve is going down all the time, gradually to zero. The growth rate is the number of individuals that grow per unit of time, and the growth rate of the S-shaped curve increases first and then decreases, reaching a maximum at t 2.

So the highest growth rate is at the beginning, and the highest growth rate is at t 2.

Harvesting should begin after the growth rate has reached its peak so as not to undermine the growth of the stock.

The growth rate is equal to the birth rate minus the death rate, and the growth rate represents the number of individuals that grow per unit of time.

The questions studied at the community level are: (taking pond ecosystems as an example) 1. How many populations are there in ponds? Which populations are numerically dominant?

2. What is the spatial structure of the biome in the pond?

3. What is the relationship between the various populations in the pond?

4What is the position of each population in the pond?

5. What is the succession of communities in the pond?

6. What is the scope and boundary of the pond?

At the community level, the study of the relationship between a species (or individuals of a species) and other organisms on a population basis. Specifically, in the title, as long as the relationship between this organism and other species of organisms belongs to the community level. It should be noted that if the relationship between the organism and individuals of the same species is at the population level, if it is with the inorganic environment, it is at the ecosystem level.

Population species, characteristics and their relationship with each other, competition, predation, etc.

The structure and characteristics of the community, the distribution of the community, etc.

A population is a group of organisms of the same species that live in the same place. For example, all macaques in a forest are one population, and all dandelions in a meadow are also a population. Modern biology considers populations to be the units of biological evolution.

Individuals in a population are not mechanically grouped together, but can mate with each other and pass on their genes to their offspring through reproduction. Therefore, the population is also the basic unit of biological reproduction.

In nature, no one population exists alone, but is closely linked to other populations through interspecific relationships. The sum of various organisms that have a direct or indirect relationship with each other in a certain natural area is called a biological community, referred to as a community. For example, in a field of farmland, there are plants such as crops and weeds, animals such as insects, birds, and rats, as well as microorganisms such as bacteria and fungi, all of which live together and are closely related to each other, thus forming a community.

Therefore, a population is made up of biological individuals, which then form species, and communities are formed between various species. Population-to-community is an inclusive relationship.

A population is a collection of creatures of the same species in the same place, excluding the environment, just like turtles in the same place, there are all kinds of them, large and small, dark in color, light, etc., and they are the population of turtles when put together.

A community is a collection of all communities in the same place (such as turtle populations, bird populations, fish populations, etc.), that is, a collection of all organisms, including bacteria and other microorganisms.

A community refers to a community in which all populations in a certain area form a community within a certain period of time. Communities can be described as small ecosystems. There are animal, plant, microbial composition.

So the community includes microorganisms and does not include the environment. For example, all the plants in a forest provide shelter and food for the animals that inhabit it, some animals can also feed on other animals, and there are a large number of microorganisms living in the soil, which live by decomposing the remains of fallen leaves, all of which form a whole called a biome.

A biome is a collection of all living things in an environment, not including the environment. Including producers, consumers, decomposers, all including bacteria.

In the case of grasslands, for example, the community includes grass, rabbits, wolves, sheep, bacteria in the soil air, and all other organisms.

The answer is yes, there is no need to doubt it; In the time, the growth rate of population A decreases from the peak to 0, so the birth rate decreases and the mortality rate increases, but the birth rate is still greater than the death rate, of course, the premise is that the growth rate = birth rate - mortality rate; During the period, population A did show an increase of "s", but during this time period, population B did not reach the maximum value, and it can be seen from the figure that population B increased in a J pattern during this time period. Over time, the growth rate of groups A and B varies differently over time, so the age composition is different.

The growth rate is first higher and then lower, as you said, the growth rate = growth rate - mortality rate, isn't it represented in the graph just those three two-way arrows? Obviously, the length of the arrow indicates the size of the growth rate, so it is increasing and decreasing.

Yes, the growth rate of the S-shaped curve is a parabola that increases first and then decreases, with the opening pointing downward. k 2 is the time when the growth rate is the largest.

The growth rate of the population is increasing first and then decreasing. When a population is born or moves into a region. Mostly due to the abundance of food and the lack of natural predators.

Population density has skyrocketed... The population growth rate is at its maximum at k2... With the intensification of intraspecific struggle and the increase in the number of natural enemies.

Declining population growth rate... Therefore, in the S-shaped growth curve, the growth of the population increases first and then decreases.

The length of the middle segment represents the growth rate, which becomes longer first and then shorter.

When the environmental capacity k is reached, the number is the largest and the density is the largest, so it is the easiest to capture.

For pests, control is most effective below k2, because when k2 is reached, the growth rate is the highest, and it is more difficult to control its growth.

For beneficial animals, the population should be controlled at k 2, because at k 2, the growth rate is the highest and the population is easy to recover.

The best time to fish is to fish at this time, the fish growth rate is fast, so fishing does not affect the number of fish populations, and the maximum daily catch of fish is obtained When the number reaches the environmental capacity k is the largest, the density is the largest, and the daily catch is naturally the largest.

Because k is the most abundant and dense, it is the easiest to capture.

k 2 is the most effective time to control, this is the time when the growth rate is the highest, the main thing is to control its growth.

1.Because there are the largest numbers;

Eradicate it in infancy), if it can eradicate this pest animal, it is the most effective control.

The k value is the maximum amount allowed for sustainable development in the current environment, and the relative density is also the largest, so it is easiest to obtain the maximum daily catch.

k 2 or less.

Because the prevention and control is to control its reproduction in a state of low growth and low rate, in terms of numbers, the fewer harmful animals, the better. In terms of rate, if the rate is high, it is always necessary to prevent and control, and the cost is high. The derivative of the s-shaped curve, first increasing and then decreasing, with a maximum value at k 2.

The value should be taken at the edge of the interval. However, when approaching k, the number is large, and in summary, it is lower than k 2....You can't take 0....

because of biodiversity).