Grade 6 Science Notes and Review Questions (DepEd-Based): Second Quarter
Quick notes in outline form and practice questions to help learners review the topics covered in Grade 6 Science (Second Quarter) based on the DepEd curriculum.
This page contains quick notes and review questions for the following topics in Grade 6 Science – Second Quarter:
Module 1: Human Body Systems: Skeletal, Integumentary, and Digestive Systems
Module 2: Human Body Systems: Respiratory, Circulatory, and Nervous Systems
Module 3/4: Animals: Characteristics of Vertebrates
Module 5: Animals: Characteristics of Invertebrates
Module 6: Ecosystem: Tropical Rainforests, Coral Reefs, and Mangrove Swamps
You can download printable (PDF) copies of the notes and the practice exam below.
Science 6: Quick Notes
Quarter 2 Module 1: Human Body Systems: Skeletal, Integumentary, and Digestive Systems
Skeletal System
Skeleton
framework of the body
consists of 206 bones (adult) that are connected by ligaments
Major functions of skeletal system:
body support
facilitation of movement
protection of internal organs
storage of minerals and fats
blood cell formation
Two divisions of the skeletal system:
axial skeleton – includes skull, vertebral column, ribs, and sternum
appendicular skeleton – includes the bones of the shoulder, arms, hands, hips, legs, and feet
Classification of bones:
long bones – limbs like arms and legs
short bones – wrist and ankles
flat bones – shoulder blades and skull
irregular bones – face and vertebrae
Selected bones:
skull – consists of:
cranium – protects the brain
facial bones
spinal column / vertebrae
protects the spinal cord
33 in child, 26 in adult
rib cage
protects the lungs and heart
12 pairs
upper 7 pairs – true ribs, connected to the breastbone
8th to 10th pairs – connected to the 7th rib by cartilage
last 2 pairs – floating ribs, not connected to sternum or other rib
scapula – bone at the back of shoulder
humerus – long bone in the upper arm
radius – the thicker of the two bones in the forearm
ulna – the longer of the two bones in the forearm
wrist or carpals – 8 bones that connect the hand to the forearm
palm or metacarpals – 5 bones
Bone marrow
found inside bones
manufacture red blood cells
two types:
red bone marrow – found in the humerus, femur, pelvis and vertebrae
yellow bone marrow – found in many other bones
Integumentary System
Integumentary system consists of:
skin
hair – helps keep you warm
nails – give structure to the ends of the fingers
glands – release oils for moisture and protection
nerves – send and receive messages to/from the brain
Functions of the integumentary system:
barrier to protect the body from the outside environment
one of the first lines of defense of the body against pathogens
helps retain body fluids, protect against dehydration
helps eliminate waste products
helps regulate body temperature
acts as a receptor for touch, pressure, pain, heat, and cold
stores water and fat
Parts of the skin:
epidermis
outer layer of the skin
outer epidermal cells secrete a protein called keratin
dermis
layer directly below the epidermis
connective tissues prevent the skin from tearing and enable it to return to normal after stretching
hypodermis
layer below the dermis
stores fats and helps the body retain heat
sweat glands
small tubular structures that produce sweat
also known as sudoriferous or sudoriparous glands
hair
hair root – part of the hair below the surface of the skin
hair shaft – visible part of the hair that protrudes through the skin
melanocytes
produce melanin, the pigment responsible for skin color
located in the epidermis
Digestive System
Digestive system is composed of:
mouth
esophagus
stomach
small intestine
large intestine
Mouth
where digestion begins
teeth – cut and grind food
saliva – moistens the food
ptyalin – enzyme in saliva that helps digest starch
Esophagus
peristalsis – rhythmic, wave-like muscle movements that push the food down
Stomach
food broken down into smaller pieces
gastric juices split proteins and fats
Small intestine
7 meters long
where final digestion takes place and food is absorbed
Large intestine
where undigested food goes
also temporarily stores water
feces – waste products of digestion
rectum – lower part of the large intestine that stores feces until elimination through the anus
Quarter 2 Module 2: Human Body Systems: Respiratory, Circulatory, and Nervous Systems
Respiratory System
Respiration
the exchange of gases with the environment
includes:
intake of oxygen
delivery of oxygen to the different parts of the body
release of carbon dioxide
Nasal cavity
nostrils – opening into the nasal passages
lined with hair and glands that produce mucus that traps impurities in the air
Pharynx
the throat
common passageway for food, water, and air
Larynx
contains vocal cords that vibrate when air passes by
Trachea
the windpipe
also filters the air we inhale
Bronchi
the two tubes that carry air into the lungs
Bronchioles
smaller tubes after the bronchi
branch off into alveoli
Alveoli
grape-like structures at the end of each bronchiole
surrounded by capillaries
the exchange of oxygen and carbon dioxide happens between the alveoli and capillaries
Lungs
main organ of the respiratory system
where gas exchange occurs
Diaphragm
dome-shaped muscle that controls breathing
located at the bottom of the lungs
Circulatory System
Circulatory system consists of:
heart
blood
blood vessels
Blood
constantly flows throughout the body
plasma – liquid part of blood
main component of blood
consists mostly of water
red blood cells
also known as erythrocytes
transport gases to and from the cells
hemoglobin – what makes the blood red, carries oxygen
white blood cells
also known as leukocytes
play a vital role in the immune system
platelets
also known as thrombocytes
smallest of the formed components of blood
help in blood clotting to stop or prevent bleeding
Blood vessels
vast networks of small tubes that carry blood throughout the body
arteries – carry oxygen-rich blood away from the heart
veins – carry deoxygenated blood back to the heart
capillaries – smallest blood vessels; serve as connection between arteries and veins
Two parts of the circulation:
pulmonary circulation – movement of deoxygenated blood from the heart and into the lungs
systemic circulation – movement of oxygenated blood from the heart to the different parts of the body
Heart
pumping organ of the body
average heartbeat – 60-100 beats per minute
atria (singular: atrium)
upper chambers of the heart
receive blood from parts of the body
ventricles
lower chambers of the heart
known as the pumping chambers
when they contract, blood is forced away from the heart
valves – overlapping tissue between atria and ventricles that allow blood to flow in only one direction
Nervous System
Nervous system
the body system that controls other parts of the body
receives signals from stimuli inside and outside of the body
main function: integrate and coordinate bodily activities
two main parts:
central nervous system (CNS) – brain and spinal cord
peripheral nervous system (PNS)
Brain
primary organ of the nervous system
cerebrum
largest part of the brain
receives sensory messages
center of emotions, consciousness, learning and voluntary movement
cerebellum
smaller, located beneath the cerebrum
coordinates involuntary and muscle action
responsible for ability to learn habits and develop skills
helps maintain sense of balance
brain stem
at the base of the brain
contains vital centers for autonomic functions
Spinal cord
cordlike material in the backbone
Peripheral nervous system
made up of nerves that branch off from the spinal cord and extend to all parts of the body
collects information from sense organs and transmits it to the CNS
deliver instructions from the CNS to the body parts that will act on them
Neuron
the nerve cell
the functional unit of the nervous system
three parts: dendrites, cell body, axon
cell body
main component of the neuron
maintains the health of the neuron
dendrites
short fibers around the cell body
carry messages into the nerve cell
axon
long fiber of the neuron
Three types of neurons:
sensory neuron
typically has long dendrites and axons
carries messages from the receptor organs (skins, eyes, nose, ears, and tongue) to the nerve center
motor neuron
typically has short dendrites and long axons
receives information from the nerve centers and transmits it to the effector organs (muscles or glands)
interneurons
connect sensory neurons to motor neurons
found only in the central nervous system
Autonomic nervous system
controls or regulates the body’s internal environment, including the vital signs
vital signs
body temperature, pulse and respiration rate, and blood pressure
reflect the condition of your internal organs
two divisions:
sympathetic
parasympathetic
sympathetic and parasympathetic
produce opposing effects
both are directly involved in maintaining the normal functions of cells
Quarter 2 Module 3/4: Animals: Characteristics of Vertebrates
Vertebrates
animals with backbone
can be:
viviparous – born live
oviparous – hatched from an egg
vertebrate groups:
mammals
fish
birds
amphibians
reptiles
Mammals
warm-blooded
viviparous (born alive)
body covering: hair or fur
have mammary glands to feed their young with milk
Fish
cold-blooded
oviparous (hatched from eggs)
body covering: scales
breathe through gills
have tails and fins to help them swim
Birds
warm-blooded
oviparous (hatched from eggs)
body covering: feathers
have a pair of:
limbs for hopping
wings for flying (some have wings but can’t fly)
use their beak or bill to get food and protect themselves
Amphibians
cold-blooded
oviparous (hatched from eggs)
body covering: moist, scaleless skin
spend part of their lives in water and part on land
examples: salamander, newt, toad, caecilian
Reptiles
cold-blooded
oviparous (hatched from eggs)
body covering: dry, scaly skin
some have shells
examples: turtles, chameleon, snake, lizard, and gecko
Quarter 2 Module 5: Animals: Characteristics of Invertebrates
Invertebrates
animals without backbones
8 main groups (mnemonic: CAMP PANE):
arthropods
mollusks
echinoderms
poriferans
cnidarians
platyhelminthes
nematodes
annelids
Arthropods
segmented bodies with jointed legs
hardened outer skeleton (exoskeleton)
largest group in the animal kingdom
further classified based on how many pairs of legs
fringing reefs – reefs that hug the shore of continents or islands
barrier reefs – reefs that stand between the open sea and a lagoon
coral atolls – reefs that enclose a lagoon
Interactions between organisms in a coral reef ecosystem:
commensalism
the organisms live together without harming one another
example: barnacles attached to the skin of turtles – the barnacles benefit, the turtle is not harmed
mutualism
both organisms benefit in the relationship
example: corals receive oxygen from the algae, the algae get protection from the corals
competition
the organisms compete for survival
example: fishes compete for source of food and space in the coral reef
predation
one organism (predator) kills another organism (prey) for food
example: a big fish eats a small fish – the big fish benefits, the small fish is harmed
parasitism
one organism (parasite) depends on another for food, protection, and reproduction
one organism benefits while the other is harmed (but not killed for food, unlike in predation)
example: worms in fish
Mangrove Swamps
The mangrove swamp ecosystem consists of:
non-living things – water, sand, mud, rocks, and sunlight
living things – a variety of marine and terrestrial life
mangrove plants – main organism that dominates the ecosystem
in the mangrove canopy – white heron (tagak) and other birds
attached to the trunk and lower branches of the mangroves – oysters, mussels
under the mangrove roots – fishes and crustaceans
migratory birds such as pelicans, spoon bills, and bald eagles
other animals such as saltwater crocodiles, monitor lizards, mudskippers, and crustaceans such as shrimps and crabs
Interactions between organisms in a mangrove ecosystem:
commensalism
barnacles and oysters attach themselves to the roots of mangroves
fish stay in the mangroves to grow and develop into mature fish
mutualism
crabs and mollusks that benefit from the mangroves also help break down plant litter in the ecosystem through grazing
predation
a white heron eating a fish
Importance of the mangrove ecosystem:
serve as breeding and nesting grounds of animal species
fish breed and nurse here before heading to the open ocean
important habitat of organisms
many animal species find protection and abundant food in this environment
natural barrier and flood defense – defend coastlines from flooding and erosion
important source of livelihood for people living in coastal areas
Practice Exam: Review Questions for First Quarter
1. How many bones does an adult human have?
a. 186
b. 196
c. 206
d. 256
2. The following are parts of the appendicular skeleton except _____.
a. carpals
b. ribs
c. tarsals
d. ulna
3. Which of the following pairings is incorrect?
a. femur – long bone
b. pinkie finger – short bone
c. skull – flat bone
d. spinal column – irregular bone
4. The outermost layer of the skin is the _____.
a. dermis
b. epidermis
c. extradermis
d. hypodermis
5. Which of the following is NOT a function of the integumentary system?
a. defense against pathogens
b. elimination of waste products
c. regulation of body temperature
d. none – all are correct
6. Digestion begins in the _____.
a. mouth
b. esophagus
c. stomach
d. small intestine
7. The rhythmic, wave-like movement of the digestive tract is called _____.
a. emesis
b. harmonic propulsion
c. peristalsis
d. traction
8. Final digestion and food absorption take place in the _____.
a. stomach
b. small intestine
c. large intestine
d. rectum
9. The part of the respiratory system that is also known as the windpipe is the _____.
a. bronchi
b. larynx
c. pharynx
d. trachea
10. The _____ are grape-like air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place.
a. alveoli
b. bronchi
c. bronchioles
d. diaphragm
11. The liquid part of the blood is called the _____.
a. blood corpuscles
b. hematocrit
c. hemoglobin
d. plasma
12. Leukocytes are also known as _____.
a. red blood cells
b. white blood cells
c. platelets
d. plasma
13. The blood vessels that carry deoxygenated blood back to the heart are the _____.
a. arteries
b. veins
c. capillaries
d. none of the above
14. How many chambers does the human heart have?
a. 2
b. 3
c. 4
d. 6
15. The system that controls and coordinates the activities of the body is the _____.
a. circulatory system
b. endocrine system
c. excretory system
d. nervous system
16. The following are parts of the brain except _____.
a. brain cord
b. brain stem
c. cerebellum
d. cerebrum
17. Which part of the nerve cell receives signals and passes them on to the main part of the cell?
a. axons
b. neurons
c. dendrites
d. cell bodies
18. Which statement is correct?
a. Sensory neurons carry messages from the brain to the effector organs.
b. Motor neurons carry messages from receptor organs to the brain.
c. Interneurons connect sensory and motor neurons in the peripheral nervous system.
d. None – all are incorrect
19. The division of the autonomic nervous system that produces opposing effects to the sympathetic nervous system is the _____.
a. parasympathetic nervous system
b. peripheral nervous system
c. somatic nervous system
d. unsympathetic nervous system
20. The following vertebrates are cold-blooded except _____.
a. amphibians
b. birds
c. fish
d. reptiles
21. Crocodiles are _____.
a. amphibians
b. cnidarians
c. flightless birds
d. reptiles
22. Which vertebrate – body covering pairing is incorrect?
a. amphibians – moist, scaly skin
b. fish – scales
c. mammals – hair or fur
d. reptiles – dry, scaly skin
23. Sponges belong to which group of invertebrates?
a. annelids
b. cnidarians
c. echinoderms
d. poriferans
24. Sea stars, sea urchins, and sea cucumbers are _____.
a. arthropods
b. coelenterates
c. echinoderms
d. mollusks
25. Which pairing is incorrect?
a. Crabs – arthropods
b. Snails – mollusks
c. Tapeworms – nematodes
d. None – all are correct
26. The topmost layer of the rainforest is the _____.
a. canopy
b. emergent
c. understory
d. forest floor
27. Pollinators such as bees drink nectar from flowers and, as they move around, carry pollen from the male part of the flower to the female part of the same or another flower. This is an example of which type of relationship?
a. commensalism
b. competition
c. mutualism
d. parasitism
28. The following are types of coral reef formations except _____.
a. atolls
b. barrier reefs
c. bleaching reefs
d. fringing reefs
29. Mudskippers are most likely found in which habitat?
a. coral reefs
b. mangrove swamps
c. tropical rainforests
d. tundra
30. Which is NOT a reason why mangrove swamps are important?
a. They serve as breeding and nesting grounds for many animal species.
b. They serve as natural barriers, protecting the coastline from flooding and erosion.
c. They are an important source of livelihood for people living in coastal areas.