myUASARevision for UASA
Questions
More
My progress
Science notes, unit 5

Plants

Textbook Science Year 2 (DLP), pages 49–60

What this chapter covers

  • You can say how plants help humans and animals (5.1.1)
  • You can name what a seed needs to germinate (5.1.2)
  • You can describe how a plant changes as it grows (5.1.3)
  • You can put the growth stages of a plant in order (5.1.4)
  • You can name the basic needs of a plant and say what happens when one is missing (5.1.5)
  • You can say why plants need nutrients (5.1.6)

Plants are all around us. In this unit you will find out why plants matter, how a seed grows into a plant and what a plant needs to stay alive.

5.1The importance of plants

Humans and animals need plants to stay alive. Plants give us food, air, medicine and habitats (homes).
Plants giveExample
FoodWe eat vegetables and fruits.
AirWe breathe fresh air near plants.
MedicineSome plants are used to treat wounds.
HabitatsBirds and monkeys live in trees.
A garden scene with banana trees, vegetables, a big tree with a monkey and birds, and people using plants for food, air and medicine
Plants give us food, air, medicine and habitats.
Did you know? Trees also give us shade, wood and rubber.

5.2Seeds and germination

Germination is when a seed starts to grow into a new plant.

A seed needs three things to germinate:

  • water
  • air
  • a suitable temperature (not too hot, not too cold)
A seed in a pot on a table, being watered and kept in a warm place until it germinates
The seed gets water, air and a suitable temperature. A few days later it germinates.
A suitable temperature is not the same for every plant. Some seeds like it warmer, some like it cooler.
Name the three things a seed needs to germinate.
Show answerHide answer
Water, air and a suitable temperature.

5.3How a plant grows

When a plant grows, it changes. It gets bigger.

As a plant grows, these increase: the number of leaves, the size of a leaf, the height of the plant and the circumference of the stem (how thick it is).
A pupil and a teacher looking at the growth stages of a maize plant: seed, germination of seed, seedling and mature plant
The maize plant grows from a seed to a tall mature plant.

A class wrote down the growth of a maize plant for 21 days.

Part of the plantDay 3Day 9Day 15Day 21
Number of leaves251014
Size of leaf (cm)1.01.51.82.5
Circumference of stem (cm)0.30.50.81.0

Every number gets bigger. The plant had 2 leaves on day 3 and 14 leaves on day 21. That is 12 more leaves.

Three green bean seedlings, on day 3, day 6 and day 9, each taller than the one before
A green bean plant on day 3, day 6 and day 9. It gets taller each time.
Look at the table. How many leaves did the maize plant have on day 15?
Show answerHide answer
10 leaves.

5.4Growth stages of a plant

A plant grows in stages. Here are the stages of a tomato plant, in order:

  1. Seed
  2. Germination of the seed
  3. Young plant
  4. Produces flowers
  5. Produces fruits
The five growth stages of a tomato plant in a circle, numbered 1 to 5: seeds, germination of seed, young plant, produce flowers, produce fruits
Growth stages of a tomato plant. The fruits have new seeds, so the circle starts again.
Remember the order: seed, germinate, young plant, flowers, fruits.
Which stage comes after the young plant?
Show answerHide answer
The plant produces flowers.

5.5What a plant needs to grow

The basic needs of a plant are water, air and sunlight. A plant also needs nutrients to grow well and stay healthy.

A plant that lacks a basic need will wither (go limp) and die. A class tested four plants of the same type and size.

Four pots: A in sunlight with no water, B in sunlight with water, C in sunlight with water but covered by a plastic bag, D inside a box with water
A has no water. B has everything. C has no air. D has no sunlight.
PlantSunlightWaterAirAfter two weeks
AyesnoyesDoes not grow well
ByesyesyesGrows best
CyesyesnoDoes not grow well
DnoyesyesDoes not grow well

Plant B grows best because it has all three needs.

A box or a plastic bag may look harmless, but it can stop sunlight or air from reaching the plant.

Nutrients. Two plants of the same type were put outside and watered. Only plant A got liquid fertiliser. Plant A grew better, because fertiliser gives nutrients.

Two potted plants A and B watered the same way, then liquid fertiliser poured into pot A
Both plants get water. Only plant A gets fertiliser.
A plant is kept in a dark cupboard. Which basic need does it lack?
Show answerHide answer
Sunlight.

Pictures: Science Year 2 (DLP) textbook, pp. 49–60 (importance p. 50, germination p. 51, maize p. 52, green bean p. 53, tomato p. 55, plants A to D p. 56, fertiliser p. 57).

Summary

TopicRemember
Importance of plantsFood, air, medicine, habitats
GerminationWater, air, suitable temperature
GrowthMore leaves, bigger leaves, taller plant, thicker stem
Growth stagesSeed, germination, young plant, flowers, fruits
Basic needsWater, air, sunlight (and nutrients)