Biology 12 Flashcards
The clitellum of earthworms
The clitellum of earthworms is responsible for secreting the cocoon that encloses the eggs during reproduction. It also produces mucus to aid in sperm transfer during mating. Additionally, it plays a role in nutrient absorption and respiration.
Diagram of euglena
Diagram of tapeworm
The rostellum is a specialized structure found in tapeworms, specifically in the scolex, which is the anterior end of the tapeworm’s body. The rostellum is equipped with hooks and/or suckers, which the tapeworm uses to attach itself to the lining of the host’s intestine.The primary function of the rostellum is to anchor the tapeworm securely to the intestinal wall of the host. Once attached, the tapeworm can absorb nutrients directly through its body surface, allowing it to thrive and grow within the host’s digestive tract. The rostellum’s hooks and suckers help the tapeworm maintain its position despite the movement of food and peristalsis in the host’s intestine.Overall, the rostellum plays a crucial role in the tapeworm’s parasitic lifestyle by ensuring a stable attachment to the host’s intestine, facilitating nutrient absorption, and enabling the tapeworm to complete its life cycle.
Sex organs bryophye
In bryophytes, which include mosses, liverworts, and hornworts, sex organs are produced in the gametophyte generation. Bryophytes exhibit an alternation of generations life cycle, consisting of a gametophyte stage and a sporophyte stage.During the gametophyte stage, which is the dominant and independent stage in bryophytes, sex organs are produced. These sex organs include:Archegonia: Archegonia are female reproductive structures that produce egg cells (or gametes) through the process of oogenesis. Each archegonium typically consists of a swollen base, a neck, and a venter containing the egg cell.Antheridia: Antheridia are male reproductive structures that produce sperm cells (or gametes) through the process of spermatogenesis. Each antheridium typically consists of a jacket layer surrounding spermatogenous tissue, which produces the sperm cells.In bryophytes, fertilization occurs when sperm cells from the antheridia swim through water to reach the archegonia, where they fertilize the egg cells to form a zygote. The zygote develops into a sporophyte, which remains attached to the gametophyte and depends on it for nutrition. The sporophyte produces spores through meiosis, which are dispersed and germinate to grow into new gametophytes, completing the life cycle of the bryophyte.
Transverse section of monocot and dicot
Sieve tubes and companion cells
Sieve tubes and companion cells are specialized structures found in the phloem tissue of vascular plants. They are primarily present in angiosperms, which are flowering plants, and are responsible for transporting organic nutrients, such as sugars and amino acids, throughout the plant.In angiosperms, sieve tubes and companion cells are closely associated and function together to facilitate the efficient transport of nutrients over long distances. Here’s a brief overview of each:Sieve Tubes: Sieve tubes are elongated cells that form the main conducting elements of the phloem. They are arranged end-to-end to form a continuous tube-like structure, known as a sieve tube member. Sieve tubes contain sieve plates at their ends, which are porous structures that allow the passage of nutrients and other phloem sap components between adjacent sieve tube members.Companion Cells: Companion cells are small, nucleated cells that are closely associated with sieve tubes. Each sieve tube member is accompanied by one or more companion cells, which are connected to the sieve tube member by plasmodesmata, microscopic channels that allow for communication and transport of substances between the two cell types. Companion cells provide metabolic support to sieve tubes by synthesizing and supplying proteins, ATP, and other molecules necessary for phloem transport.Together, sieve tubes and companion cells form a functional unit called a sieve tube-companion cell complex, which plays a crucial role in the translocation of organic nutrients, such as sugars produced during photosynthesis, from photosynthetic tissues (sources) to non-photosynthetic tissues or growing regions (sinks) throughout the plant. This process, known as translocation, is essential for supplying energy and building blocks to support plant growth, development, and metabolism.
Organ of perenation in plants
An organ of perennation in plants is a specialized structure that allows a plant to survive adverse environmental conditions, such as drought, cold temperatures, or lack of sunlight, and resume growth when conditions become favorable. These organs typically store nutrients or energy reserves, protect meristematic tissues, and enable the plant to regrow or reproduce in the next growing season.One example of an organ of perennation is the bulb. A bulb is a modified underground stem surrounded by thick, fleshy scales or leaves that store food reserves, such as starches and sugars. Bulbs enable perennial plants to survive unfavorable conditions, such as winter cold or dry spells, by storing energy and protecting vital meristematic tissues, such as the shoot apical meristem. Common examples of bulb-forming plants include tulips, onions, daffodils, and lilies.Other examples of organs of perennation include:Rhizomes: Underground horizontal stems that store food reserves and produce new shoots and roots. Examples include ginger and irises.Tubers: Enlarged, fleshy underground storage structures that store food reserves and produce new shoots. Examples include potatoes and yams.Corms: Short, swollen underground stems surrounded by dry, papery scales that store food reserves and produce new shoots. Examples include crocuses and gladioli.Stolons (Runners): Horizontal stems that grow along the soil surface and produce new shoots and roots at nodes. Examples include strawberries and spider plants.These organs of perennation enable plants to survive unfavorable conditions and ensure their long-term survival and reproductive success.
Difference vetween plant and animal growth
0Cell Division and Differentiation:In animals, growth primarily occurs through cell division (mitosis) and subsequent differentiation, where undifferentiated cells specialize into specific cell types to form tissues, organs, and organ systems.In plants, growth occurs mainly through cell division at meristematic regions called apical meristems, located at the tips of roots and shoots. Unlike animal cells, most plant cells retain the ability to divide and differentiate throughout their lifespan, allowing for continuous growth and development.
Tissue Organization:Animals have distinct tissues organized into organs and organ systems, each with specialized functions. These tissues include epithelial, connective, muscle, and nervous tissues.Plants also have tissues, including dermal, ground, and vascular tissues, but they lack organs and organ systems in the same sense as animals. Instead, plants have modular growth, where new organs (leaves, stems, roots) arise from meristems and are added to existing structures.
Growth Patterns:Animal growth tends to be determinate, meaning that individuals reach a maximum size and undergo relatively limited growth after reaching maturity. Growth may continue in certain tissues (e.g., bone remodeling) or during specific life stages (e.g., puberty), but overall growth is finite.Plant growth is typically indeterminate, meaning that growth continues throughout the plant’s life. Plants can exhibit both primary growth (lengthening) and secondary growth (thickening), allowing them to increase in size and volume indefinitely under favorable conditions.
Environmental Factors:Animal growth is influenced by various environmental factors, including nutrition, hormonal regulation, genetics, and external factors such as temperature and habitat conditions.Plant growth is also influenced by environmental factors, including light, water, temperature, nutrients, and soil composition. Plants exhibit plasticity in response to environmental cues, adjusting their growth patterns and morphology accordingly.Overall, while animals and plants both undergo growth processes to increase in size and complexity, the mechanisms and patterns of growth are distinct due to their unique physiological and structural characteristics.
Dental formula omnivore
Omnivore:
• Dental Formula: 2 × (I 3/3, C 1/1, P 4/4, M 2/3) = 32 teeth
• Key Points:
• Omnivores have a combination of sharp, pointed teeth (canines) for tearing meat and broad, flattened teeth (molars) for grinding plant material.
• Incisors (I) are used for cutting and shearing food.
• Canines (C) are used for piercing and tearing meat.
• Premolars (P) and molars (M) have ridges and cusps for grinding and crushing both plant and animal matter.
• Adapted to consume a varied diet consisting of both animal and plant material.
Dental formula detritus feeder
Detritus Feeder (Scavenger):
• Dental Formula: Varies among species, but typically similar to omnivores.
• Key Points:
• Detritus feeders often have a similar dental structure to omnivores, with a combination of incisors, canines, premolars, and molars.
• Their teeth may be adapted for processing a wide range of food items, including carrion, decaying matter, insects, and plant material.
• Well-suited for feeding on a diverse array of organic matter found in detritus and decaying organic material.
Dental formula carnivore
Carnivore:
• Dental Formula: 2 × (I 3/3, C 1/1, P 3/2, M 1/1) = 30 teeth
• Key Points:
• Carnivores have sharp, pointed teeth (canines and carnassial teeth) for capturing, killing, and tearing flesh.
• Incisors are used for gripping and tearing meat.
• Canines are long and pointed for piercing and holding prey.
• Premolars may be reduced or absent, and molars are often blade-like (carnassial teeth) for shearing flesh.
• Specialized for hunting and consuming animal prey, with little adaptation for processing plant matter.
Dental formula herbivore
Herbivore:
• Dental Formula: Varies among species, but typically characterized by a large number of molars.
• Key Points:
• Herbivores have broad, flat teeth (molars and premolars) for grinding and crushing fibrous plant material.
• Incisors may be specialized for cutting and cropping vegetation.
• Canines are usually reduced or absent in herbivores, as they are not necessary for consuming plant matter.
• Premolars and molars have ridges and cusps for grinding tough plant material and cellulose.
• Adapted for efficiently processing and digesting large quantities of plant material as the primary source of nutrition.
The dental formula for humans is:
2 × (I 2/2, C 1/1, P 2/2, M 3/3) = 32 teeth
Here’s a breakdown of the teeth and their functions:
• Incisors (I): Used for cutting and shearing food. Humans have a total of 8 incisors, with 4 in the upper jaw (2 central incisors and 2 lateral incisors) and 4 in the lower jaw (same arrangement). • Canines (C): Also known as “eye teeth” or “cuspids,” canines are pointed teeth used for tearing and gripping food. Humans have a total of 4 canines, with 2 in the upper jaw and 2 in the lower jaw. • Premolars (P): Premolars, also called bicuspids, have flat surfaces with ridges and are used for crushing and grinding food. Humans have a total of 8 premolars, with 4 in the upper jaw (2 on each side) and 4 in the lower jaw (same arrangement). • Molars (M): Molars are the largest teeth and have broad, flat surfaces with multiple cusps. They are primarily used for grinding and chewing food. Humans have a total of 12 molars, with 6 in the upper jaw (3 on each side, including the wisdom teeth) and 6 in the lower jaw (same arrangement).
Overall, the human dental formula reflects the omnivorous diet of humans, with a combination of teeth suited for cutting, tearing, and grinding a variety of food items, including plant material, meat, and other food sources.
Seed is not an organ of perennation
No, a seed is not considered an organ of perennation in plants.
In plants, organs of perennation are specialized structures that enable the plant to survive adverse environmental conditions and resume growth when conditions become favorable. These structures typically store nutrients or energy reserves, protect vital meristematic tissues, and allow the plant to regrow or reproduce in the next growing season.
Common examples of organs of perennation in plants include bulbs, rhizomes, tubers, corms, and stolons, which are specialized underground or modified structures that store energy reserves and protect vital tissues during unfavorable conditions.
A seed, on the other hand, is the mature ovule of a flowering plant, containing an embryo plant and stored nutrients surrounded by a protective seed coat. While seeds play a crucial role in plant reproduction and propagation, they are not considered organs of perennation because they do not serve the purpose of enabling the plant to survive adverse conditions and regrow in subsequent growing seasons.
Instead, seeds are primarily involved in the dispersal and germination of new plants, allowing for the propagation and continuation of plant species. Once conditions are favorable for germination, seeds undergo processes such as imbibition, dormancy breaking, and embryo growth to initiate the development of a new plant.
Alternation of generation
Alternation of generations is a characteristic life cycle pattern found in plants and certain algae, where two distinct multicellular phases, the gametophyte and sporophyte generations, alternate in the life cycle. Here are the key points of alternation of generations:
1. Two Distinct Phases: • The life cycle of organisms exhibiting alternation of generations includes two multicellular phases: the gametophyte and sporophyte generations. 2. Gametophyte Generation: • The gametophyte generation is haploid (n) and produces gametes (eggs and sperm) through mitosis. • Gametophytes are typically smaller and simpler in structure compared to sporophytes. • Gametes are produced within specialized structures called gametangia, which may be male (antheridia) or female (archegonia). 3. Fertilization: • Fusion of gametes (fertilization) results in the formation of a diploid (2n) zygote. • Fertilization typically occurs within or near the archegonium, where the egg is located. 4. Sporophyte Generation: • The zygote develops into the sporophyte generation, which is diploid (2n) and produces spores through meiosis. • Sporophytes are typically larger and more complex in structure compared to gametophytes. • Spores are produced within specialized structures called sporangia, which may be located on the sporophyte. 5. Spore Dispersal and Germination: • Spores are dispersed and germinate to give rise to new gametophyte individuals. • Spores are haploid (n) and develop into multicellular gametophytes through mitotic divisions. 6. Cycle Continues: • The alternation of generations life cycle continues as the gametophyte and sporophyte generations alternate indefinitely. • Each generation gives rise to the other, ensuring the perpetuation of the species. 7. Adaptation to Terrestrial Life: • Alternation of generations is believed to have evolved as an adaptation to the transition from aquatic to terrestrial environments. • It allows plants to disperse and reproduce effectively on land while minimizing the risk of desiccation and ensuring genetic variation.
Overall, alternation of generations is a complex life cycle pattern that enables plants and certain algae to undergo both sexual and asexual reproduction, adapt to diverse environments, and ensure the continuation of their species.
Alternation of generation
Many plant species exhibit alternation of generations in their life cycle. Here are some examples of plants with alternation of generations:Mosses (Bryophyta):Mosses are small, non-vascular plants that typically grow in damp, shaded environments.Their life cycle includes a dominant gametophyte generation and a smaller sporophyte generation.The gametophyte produces gametes within specialized structures called gametangia, while the sporophyte produces spores within sporangia.Ferns (Pteridophyta):Ferns are vascular plants that reproduce by spores and typically grow in moist, shaded habitats.Their life cycle includes a dominant sporophyte generation and a smaller gametophyte generation.The sporophyte produces spores through meiosis, which develop into the gametophyte generation, where gametes are produced.Clubmosses (Lycophyta):Clubmosses, also known as ground pines or lycopods, are small vascular plants that reproduce by spores.Their life cycle includes a dominant sporophyte generation and a smaller gametophyte generation.Sporophytes produce spores in specialized structures called sporangia, which develop into gametophytes where gametes are produced.Seed Plants (Gymnosperms and Angiosperms):Gymnosperms, such as conifers and cycads, and angiosperms (flowering plants) also exhibit alternation of generations, although their life cycles are more reduced compared to non-seed plants.In gymnosperms, the sporophyte generation is dominant, and cones produce spores that develop into the gametophyte generation.In angiosperms, the sporophyte generation is dominant, and flowers produce gametes (pollen grains and ovules) that unite to form seeds.These are just a few examples of plants with alternation of generations. The specific details of their life cycles may vary, but they all share the characteristic alternation between multicellular gametophyte and sporophyte generations.
Cerebrum
Cerebrum:
• The cerebrum is the largest part of the brain and is divided into two hemispheres (left and right) connected by the corpus callosum.
• Function:
• Higher Cognitive Functions: The cerebrum is responsible for higher cognitive functions, including reasoning, problem-solving, decision-making, and creative thinking.
• Sensory Perception: It receives and processes sensory information from the environment, including touch, vision, hearing, taste, and smell.
• Motor Control: The cerebrum controls voluntary movements of skeletal muscles, allowing for precise and coordinated movements.
• Language and Speech: It plays a crucial role in language processing, speech production, and comprehension.
• Memory: The cerebrum is involved in the formation, storage, and retrieval of memories, both short-term and long-term.
• Emotions: It regulates emotions and emotional responses, including pleasure, fear, and motivation.