Science ASP Grade 7 – Elite stream

Sections: 1,2 and 3Teacher: Esra’ M. Jaradat

Dear future scientists,

Use this study helper to revise and study for the exam

If you wanted help go back to the PPTs of lessons 1 – 3 and you can contact me at anytime on teams

Thank you

Teacher Esra' M.Jaradat

Unit 2: Life structure and functionModule 2: Body Systems

Lesson 3Obtaining Energy and Removing wastes

Study Helper

Textbook pages 38 - 49

Teacher Esra' M.Jaradat

Importance of food:1. Source of energy to carry out their cell functions.2. Provides building blocks for growth and repair of tissues.

Calorie The amount of energy it takes to raise the temperature of 1 kg of water by 1◦C

Nutrients The parts of food used by the body to grow and survive like calcium and proteins

The amount of energy a person needs depends on:

Weight , Age, Activity level and Gender Teacher Esra' M.Jaradat

The digestive system

Tongue

Salivary glands

Esophagus

Stomach

Small intestine

Large intestine

Teacher Esra' M.Jaradat

Functions of digestive system

Ingestion Digestion Absorption Elimination

PeristalsisFood moves through the esophagus and the rest of the digestive tract (stomach, small and large intestines) by waves of smooth muscle

contractions.Teacher Esra' M.Jaradat

Path of food

All these are holloworgans (empty from inside) so food can pass through

Teacher Esra' M.Jaradat

Types of digestion

Mechanical digestion Chemical digestion

Food is physically broken into small pieces through grinding, mashing and chewing.

Food is chemically broken into small molecules

Done by teeth and tongue and by peristalsis

Done by enzymes

• Make it easier for swallowing • Increase the surface area of food

molecules to prepare food for chemical digestion

Note: Chemical digestion starts in the mouth, continues in the stomach and is completed in

small intestine

Teacher Esra' M.Jaradat

Mechanical digestion

Chemicaldigestion

Teeth and tongue

• Chewing• Grinding • Mashing

Saliva

• Enzyme that digests carbohydrates• Substance that neutralizes acidic food

Mouth

Saliva is secreted by salivary glands

Teacher Esra' M.Jaradat

Muscular tube that connects the mouth to the stomach.

Esophagus

Mouth

Esophagus

Stomach Teacher Esra' M.Jaradat

Stomach

Stomach connects esophagus to small intestine

Esophagus

Stomach

Small intestine

Teacher Esra' M.Jaradat

Functions of stomach

1. Temporarily store food

Stomach has folds that allow the stomach to expand and store food for few hours.This allows you to go many hours between meals.

2. Chemical digestion

• The cells of the stomach secretes gastric juice.

Gastric juice contains:Gastric acid: to break down the structures that hold the plant and animal cells together

Stomach

Teacher Esra' M.Jaradat

• Where most chemical digestion occurs (digestion of all types of

food: fats, proteins, carbohydrates and nucleic acids)

• Where nutrients and water absorption occurs by villi

• Villi are finger-like projections cover the folds of the small

intestine, each villus has blood vessels

• In villi, nutrients leave the small intestine and go to blood through capillaries

Small intestine

Teacher Esra' M.Jaradat

Folds in small intestine

covered with villi One villus

Blood vessels

Lymph vessel

Teacher Esra' M.Jaradat

Materials that pass in the large intestine are the waste products of digestion (food that is not digested or not absorbed)

Functions of large intestine:

• Absorb any remaining water

• Release of wastes (semisolid) to the outside of body

Large intestine

Teacher Esra' M.Jaradat

Functions of the Excretory System

1. Collect and eliminate wastes

2. Regulation of fluids

Teacher Esra' M.Jaradat

The excretory system is made of 4 systems

System Type of wastes eliminated

Respiratory Waste gases: carbon dioxide and water vapor

Urinary Liquid wastes

Digestive Solid wastes (undigested food)

Skin Excess water and salts through sweating

Teacher Esra' M.Jaradat

How do plants obtain energy and remove waste?

• Plants make their own food through a process called photosynthesis

• Photosynthesis is a series of chemical reactions that use light energy and covert it to usable energy for the cell

• Plants need carbon dioxide, water and light energy to make oxygen and glucose (sugar molecules as food)

Teacher Esra' M.Jaradat

• Roots absorb water and minerals from soil, then they move through xylem to reach all parts of plants

• Leaves make food and it moves through phloem to reach all parts of plant

• Gases in plants pass through stomata (tiny holes in the surface of plant’s leaf)

How do plants obtain energy and remove waste?

Teacher Esra' M.Jaradat

Teacher Esra' M.Jaradat