Plant and Animal Nutrients

• Plants and animals both require nutrients for survival, obtained and processed in different ways

Nutrients

• Nutrients are essential compounds in foods that provide energy, aid in repair and growth, and regulate chemical processes
• The six major nutrients are carbohydrates (CHO), lipids (fats), proteins, vitamins, minerals, and water

Plant Nutrients

• Plant nutrition involves the supply and absorption of chemical compounds for growth and metabolic processes
• These compounds are known as plant nutrients or essential elements, including water, carbon dioxide, and essential elements

Water for Plants

• Water helps transport important nutrients within plants

Carbon Dioxide for Plants

• Carbon dioxide, a gas consisting of one carbon and two oxygen atoms, is crucial for plants to produce carbohydrates through photosynthesis

Essential Elements for Plants

• Plant biologists have identified 17 elements as essential for plants

Functions of Essential elements for Plants

• Carbon, hydrogen, and oxygen are major components of organic plant material and aid in oxidation-reduction reactions
• Boron is involved in cell wall synthesis, enzymatic reactions, metabolic pathways, and mitotic activity
• Calcium is a structural component of the cell wall and cell membrane, serving as a counter-ion in the vacuole
• Chlorine is essential for the water splitting system in photosystem II and regulates stomatal opening
• Copper is a cofactor for metalloproteins and enzymes, involved in photosynthetic electron transport, cell wall metabolism, hormone signaling, and oxidative stress response
• Iron regulates proteins and metabolites in roots and leaves
• Magnesium is important for chlorophyll synthesis and as a cofactor in activating ATPase
• Manganese is involved in photo destruction of chlorophyll and chloroplast structure, acts as an enzyme activator, and serves as a precursor for amino acids, hormones (auxins), and lignin
• Molybdenum activates enzymes like nitrate reductase, catalase, and ribonuclease, and aids in chlorophyll synthesis
• Nickel supports endosperm development, dehydrogenase activity, and urea breakdown and promotes root nodule growth
• Nitrogen is necessary for general plant growth in roots, stems, leaves, flowers, and fruits and also aids in chlorophyll synthesis
• Phosphorus transfers energy during photosynthesis and respiration (ADP-ATP synthesis) and is a structural component of phospholipids, nucleic acids, coenzymes, and nucleotides
• Potassium facilitates cell extension and stomatal regulation, activates enzymes (kinase, starch synthase, and nitrate reductase), and supports photosynthetic activity (CO2 fixation and pH regulation)
• Sulfur aids in the assimilation of oxidation-reduction reactions and participates in various enzymatic processes
• Zinc is essential for enzymatic function and reactivity, stem elongation, and protein and starch synthesis

Routes for Absorption in Plant Roots

• Symplast route involves the continuous arrangement of protoplasts interconnected by plasmodesmata
• Apoplast route involves the non-protoplasmic components of a plant, including the cell wall and intracellular spaces

Specialized Absorptive Structures in Plants

• Root hairs are slender extensions of specialized epidermal cells that greatly increase surface area for absorption
• Root nodules are localized swellings in roots where bacterial cells exist symbiotically with the plant
• Mycorrhizae represent a symbiotic interaction between a young root and a fungus

Nutritional Adaptations in Plants

• Plants form symbiotic relationships with soil microbes because they lack the nitrogenase enzyme needed to convert diatomic nitrogen into usable forms
• Soil bacteria, or rhizobia, perform biological nitrogen fixation, converting atmospheric nitrogen gas (N₂) into ammonia (NH3)
• Most plants form mycorrhizae with fungi due to depleted soil nutrients
• The symbiotic relationship benefits the plant by obtaining phosphate and the fungus by obtaining sugars
• Fungal hyphae increase the plant's root surface area, extending beyond nutrient-depleted zones

Symbiotic Relationships

• Symbiotic relationships play a significant role in driving evolution by enhancing species survival through cooperation

Other Forms of Nutritional Adaptation

• Saprophytes acquire nutrients from dead matter using enzymes to convert organic compounds into simpler forms
• Predation involves one organism (the predator) killing and consuming another (its prey)
• Parasitic plants acquire some or all of their nutrients from a host plant, relying on it for survival

Animal Nutrition

• Animals have developed ways to obtain, process, and digest food as heterotrophs
• Animal nutrition focuses on dietary nutrient needs in agriculture, food production, zoos, aquariums, and wildlife management

Major Classes of Nutrients for Animals

• Carbohydrates provide energy in the form of calories, primarily as glucose for body tissues and cells
• Fats, also called fatty acids or lipids, consist of three molecules joined as "triglycerides" and serve as concentrated energy sources necessary for young children
• Fiber is a mixture of undigested carbohydrates that add bulk to food and soften feces, aiding in preventing constipation and slowing nutrient absorption
• Proteins are essential for growth, improving immune function, making hormones and enzymes, repairing tissue, preserving muscle mass, and supplying energy and are especially important for children, teens, and pregnant women
• Minerals are less common elements in the diet that act as electrolytes
• Vitamins are groups of related substances in small amounts that are classified as either fat-soluble (A, D, E, K) or water-soluble (B, C, and folic acid)

Importance of Water

• Humans survive only a few days without water, needing 2-3L daily
• Water aids in producing cells, fluids, sweat for cooling, supports essential body processes, keeps linings of organs moist, and produces urine

Feeding Mechanisms of Animals

• Substrate-feeders live in or on their food source, like earthworms and caterpillars
• Filter-feeders are aquatic animals that draw in water and strain small organisms, such as whales and coelenterates
• Fluid-feeders suck fluids from a living host, like mosquitoes and leeches
• Bulk-feeders eat large chunks of food using adaptations like jaws and teeth, such as snakes, cats, and humans

Food Processing in the Human Digestive System:

• The oral cavity chews food and mixes it with saliva from three pairs of salivary glands
• The pharynx serves as the entrance to the esophagus and trachea, using the epiglottis to prevent food from entering the trachea
• The esophagus connects the pharynx to the stomach and transports food via peristaltic contractions that occurs in rhythmic waves

Human Digestive System: Stomach, Small Intestine, and Accessory Organs

• The stomach is a stretchable sac that mixes and stores food, secretes gastric juice to dissolve and degrade food, regulates passage of food to the small intestine
• The small intestine is 6 meters long and contains the duodenum, jejunum, and ileum
• Most enzymatic hydrolysis occurs in the duodenum within the first 25 cm of the small intestine
• The liver secretes bile for emulsifying fats which is then stored in the gallbladder
• The pancreas secretes enzymes that break down food molecules, buffers against HCl from the stomach, and insulin for controlling glucose metabolism

Human Digestive System: Large Intestine and Rectum

• The large intestine is about 1 meter long and concentrates undigested matter by absorbing mineral ions and water
• Fluid, sodium, and vitamin K are absorbed
• The rectum is a short extension of the large intestine where undigested food is stored and pushed through for the excretion of feces through the anus