Science – Grade 8 Review: Digestive System, Genetics, and Photosynthesis

A comprehensive set of practice flashcards covering digestion, excretion, genetics, and photosynthesis based on the provided notes.

What is food?

A chemical substance used by any living organism to sustain growth, repair, life, and to maintain health and vital processes.

What is glycogen and when is it used?

Glycogen is the storage form of glucose; it is converted into usable energy when we do not eat, supporting breathing and brain function.

What is borborygmus?

A gurgling sound of fluid and gas movements in the intestine, signaling hunger when the stomach is empty.

Name the six major classes of nutrients.

Carbohydrates, Vitamins, Proteins, Minerals, Fats, and Water.

What are the two types of hunger?

Biological hunger (stomach is empty) and Psychological hunger (mind tells us we are hungry).

What are examples of starchy carbohydrates?

Bread, Rice, Potatoes, and Pulses.

What are the roles of proteins in the body?

They compose muscles, hair, skin, and organs; provide energy when glycogen is depleted; are necessary for antibodies.

List some protein sources.

Fish, Almonds, Broccoli, Nuts, Sprouts, Milk, Chicken, Oats, Eggs, Seeds, Greek yogurt.

What do fats provide and what is a health risk of excess fat?

Fats provide more energy than carbohydrates and protein and act as insulation; excess fat can contribute to health problems like atherosclerosis.

Do vitamins and minerals provide energy?

No, they do not provide energy; they are necessary for various body processes and help absorb nutrients.

What is the role of water in the body?

Water makes up about 60% of the body, aids digestion, and can relieve headaches, fatigue, and joint discomfort.

What are the four major phases of the digestive system?

Ingestion, Digestion, Absorption, Elimination.

What is the difference between mechanical and chemical digestion?

Mechanical digging involves chewing and mixing; chemical digestion uses enzymes to break down molecules.

What is absorption?

The process by which smaller molecules enter cells after digestion.

What is elimination?

Also called excretion; the removal of undigested and absorbed wastes via the anus.

Name three accessory organs of digestion.

Liver, Gall Bladder, Pancreas.

What is a bolus?

A ball-like mass of food that travels down the pharynx to the stomach.

What is the epiglottis and its function?

A flap that closes the windpipe during swallowing to prevent food from entering the airway.

What is peristalsis?

The wave-like muscular movements that move the bolus from the pharynx to the stomach.

What are the major parts of the stomach?

Fundus, Cardia, Body, and Pylorus, with the pyloric sphincter controlling backflow.

What are the components of gastric juice and their roles?

Mucin (protects stomach lining), Pepsinogen (inactive enzyme activated to digest protein), Hydrochloric acid (activates pepsinogen and destroys microorganisms).

What are the three regions of the small intestine and their roles?

Duodenum receives chyme and continues digestion; Jejunum is the middle section where most absorption occurs; Ileum is the final section where nutrient absorption continues.

What are villi and their function?

Hair-like projections on the lining of the small intestine that increase surface area for nutrient absorption.

What are the five sections of the large intestine and its primary function?

Cecum, Ascending, Transverse, Descending, and Sigmoid; primarily water reabsorption and waste formation.

What is the function of the appendix?

Attached to the Cecum; the notes mention it in the context of the large intestine's structure.

What are the liver, gall bladder, and pancreas responsible for?

Liver: produces bile and stores glycogen; Gall Bladder: stores bile; Pancreas: produces digestive enzymes and helps regulate blood sugar.

What excretory roles does the skin have?

The skin excretes waste via sweat glands through the pores (sweat).

What are the kidneys and nephrons responsible for?

The kidneys filter blood; nephrons filter wastes and return essential substances to the blood; urine is produced through filtration, reabsorption, and excretion.

What are filtrate, reabsorption, and excretion?

Filtrate is filtered material from blood; reabsorption returns substances to the blood; excretion removes urine from the body.

What excretory organs exist besides the kidneys?

Rectum, Skin, and Lungs (sweat and respiration products).

What are genes and traits?

Genes determine traits; traits are divided into Species Traits and Individual Traits.

What is heredity and genetics?

Heredity is the passing of traits from parents to offspring; Genetics is the science that studies heredity.

What is phenotype vs genotype?

Phenotype: observable characteristics (often dominated by dominant traits); Genotype: the genetic makeup (DNA sequence).

What is a Punnett square used for?

To predict possible genotypes and phenotypes of offspring.

What is meant by homozygous and heterozygous?

Homozygous: identical alleles (AA or aa); Heterozygous: different alleles (Aa).

What is dominance and recessiveness in genetics?

Dominant traits appear with one or two copies; recessive traits appear only when two copies are present.

What is an allele?

A form of a gene; can be dominant or recessive.

Who is considered the father of genetics and what did he study?

Gregor Mendel; Austrian monk who studied pea plants and formulated three laws of inheritance.

What are Mendel’s three laws of inheritance?

1) Principle of Dominance and Recessiveness, 2) Principle of Segregation, 3) Principle of Independent Assortment.

What is a monohybrid cross and a dihybrid cross?

Monohybrid crosses involve one trait; dihybrid crosses involve two traits, often considering heterozygous parents.

What are photosynthesis and cellular respiration?

Photosynthesis is the process by which plants convert light energy, CO2, and water into glucose and O2; cellular respiration breaks down glucose with O2 to produce ATP, CO2, and water.

What is the overall photosynthesis equation?

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2.

What is the overall cellular respiration equation?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP.

What is the relationship between photosynthesis and cellular respiration?

Photosynthesis provides glucose and O2 for respiration; respiration releases energy (ATP) and produces CO2 and H2O, which are used again in photosynthesis.