1. Reproductive types: including asexual reproduction and sexual reproduction.
2. The offspring produced by sexual reproduction have the genetic characteristics of parents and are formed by the combination of male and female gametes.
3. The significance of sexual reproduction: it has greater viability and variability, so it is of great significance to the survival and evolution of organisms. For sexually reproducing organisms, the starting point of individual development is the fertilized egg.
4. Types of asexual reproduction: budding reproduction, fission reproduction, spore reproduction and vegetative reproduction.
process
for instance
divide
1 mother and 2 new individuals
Single-celled organisms such as bacteria and amoeba.
Germination propagation
Maternal bud new individual
Yeast and hydra
spore reproduction
New individual of mother spore
Fungi, actinomycetes, ferns, etc.
vegetative propagation
New individuals of roots, stems and leaves
Advanced factory
5. Significance and application of asexual reproduction: The key is that the offspring produced by asexual reproduction keep the mother's traits unchanged. If the mother has some excellent traits that need to be preserved and propagated in large quantities, then asexual reproduction provides us with a theoretical basis. Therefore, cutting and grafting are widely used in agricultural production to propagate excellent varieties of flowers and fruit trees.
The difference between sexual reproduction and asexual reproduction:
asexual reproduction
sexual reproduction
discrepancy
Mother's body
Only one parent is involved.
Usually both parents are involved.
Reproductive process
(Generally) No, even if there is (spore), there is no gender difference and no combination.
Yes, and there are gender differences. Generally speaking, it needs two two combination.
Reproductive process
Directly produce new individuals from the mother.
Generally, it is a new individual with sexual germ cells, and it can also be a new individual with sexual germ cells (such as parthenogenesis)
Character maintenance
Its descendants are the direct continuation of the mother, with little variation, and can maintain the characteristics of the Qin Dynasty.
Their offspring are recombinants of their parents' genetic materials, which have many variations, which is not conducive to the maintenance of Qin dynasty traits.
Survival ability of future generations
There is a downward trend.
Have strong vitality.
Impact on race
If this method of reproduction is used for a long time, the race will decline.
Let the race prosper.
The role of evolution
No promoting effect
Have a promoting effect
similar
Is to produce new individuals and breed offspring, so that the race can continue.
Knowledge expansion:
1. In asexual reproduction, the division and reproduction of prokaryotes such as bacteria does not belong to mitosis, but a special "binary division" way, which forms two offspring bacteria, but it does not belong to amitosis.
2. Mitosis is a division mode of eukaryotic cells. According to the totipotency of plant cells, a new asexual propagation technique has been developed in recent decades? Tissue culture of plants (cloning technology).
Callus is a cell mass formed by undifferentiated amorphous parenchyma cells produced by cell division under aseptic conditions. The advantages of plant tissue culture are: less materials, short culture cycle, high reproduction rate and convenient automatic management. At present, this technology has been widely used in the rapid propagation of flowers and fruit trees and the cultivation of virus-free plants.
Related high school biology knowledge points: elements in cells
Chemical elements that make up cells:
(1) element type:
Macroelements: carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, potassium, calcium, magnesium, etc.
Trace elements: zinc, molybdenum, copper, boron, iron and manganese.
(2) Classification basis: According to the content of macro elements, trace elements account for one ten thousandth of the total biomass.
The relationship between the biological world and the non-biological world;
Elements that make up an organism can be found in the abiotic world, but their contents are quite different, which reflects the difference between the biotic world and the abiotic world.
consistent
different
include
(1) Both biological and abiotic worlds are made up of chemical elements.
② Chemical elements that make up cells can be found in inorganic nature, and no element is unique to cells.
The contents of chemical elements that make up organisms are quite different between organisms and inorganic substances.
cause
(1) Life originated in the non-living world.
② The chemical elements that make up organisms are obtained from inorganic nature.
Organisms selectively obtain their own substances from inorganic nature.
Characteristics of elements:
Although the content of trace elements in organisms is very small, they play an important role in the life activities of organisms;
(1) Zinc and iron are trace elements, which can be obtained from food. If you deliberately supplement it, it may be harmful to your health. Boron can affect the germination of pollen and the elongation of pollen tubes, and lack of boron will produce the phenomenon of "flowers without fruit"
(2) Zinc deficiency in plants will affect the production of auxin (IAA); Auxin deficiency will affect the growth and development of crops; Zinc is a trace element.
(3) Magnesium is the main element of plant chlorophyll.
(4) Iron is the main element of animal hemoglobin, and iron deficiency can lead to anemia.
(5) Iodine is the main component of thyroid hormone. Iodine deficiency in adults can lead to endemic goiter (big neck disease), and iodine deficiency in children can lead to dementia.
Knowledge counseling:
1, the contents of C, H, O and N are the most, regardless of dry cell weight or fresh weight.
2. The relative content of heavy elements in fresh human cells: O >；; C & gtH & gtN & gtP & gts； The relative content of elements in the weight of human stem cells: C>O>N>H & gtCa & gtP>s.
3. Macroelements and trace elements are necessary for the life activities of organisms, and they are distinguished according to their contents rather than their functions.
4. The types of chemical elements in different organisms are roughly the same, but the contents of various elements are quite different.
5. Fresh weight refers to the weight of organisms (or cells) measured under natural living conditions; Dry weight refers to the weight measured by an organism (or cell) after removing water. The element that accounts for the freshest weight of human body is O, and the element that accounts for the driest weight of human body is C.
Classification of elements in cells:
C (maximum content under dry weight) O (maximum content under fresh weight)
The main elements of human cells;
Biology-related knowledge points in senior high school: types of immune regulation
Types of immunomodulation:
Types of immune regulation: including nonspecific immunity and specific immunity.
1. Nonspecific immunity: It includes the first line of defense of human immunity consisting of skin and mucosa and the second line of defense consisting of bactericidal substances and phagocytes in body fluids. It is innate, not for a specific pathogen.
2. Specific immunity (the third line of defense)
(1): It is mainly composed of immune organs and immune cells by means of blood circulation and lymphatic circulation.
(2) Function: Resist foreign pathogens and inhibit tumors.
(3) Mode: humoral immunity and cellular immunity.
(4) Process
① Humoral immunity:
② Cellular immunity
(4) Active immunization: a method of using antigens to stimulate the body to produce antibodies instead of directly introducing antibodies from the outside. Active immunity has strong resistance to subsequent infection. It can be produced by the disease pathogen itself or by immunization (using inactivated or attenuated vaccines or toxoids). Immunity takes days, weeks or even longer, but it can be maintained for a long time or even for life, and the required antigen can be easily reactivated by injection.
(5) Passive immunity: The corresponding immunity obtained by the organism by acquiring exogenous immune effector molecules (such as antibodies) or immune effector cells.
The difference between active immunization and passive immunization: active immunization with inactivated or attenuated antigens and passive immunization with antibodies.
Knowledge counseling:
Methods of judging humoral immunity and cellular immunity;
1. According to the result of immunization, if the target cell is lysed by immunization and the hidden antigen is released, it is cellular immunity; If two components combine to form a precipitate or cell mass, it is humoral immunity.
2. According to the antigen type: if the antigen only enters the body fluid, it is humoral immunity; If the antigen enters the tissue cells, it is cellular immunity.